^^fe^ \^mm/%f^'^ PUBLISHED UNDER THE SUPERINTENDENCE OF THE SOCIETY FOR THE DIFFUSION OP USEFUL KNOWLEDGE. THE LIBRARY ENTERTAINING KNOWLEDGE. INSECT TRANSFORMATIONS. COMMITTEE. ChoirnMfl— The Right Hon. LORD BROUGHAM, F.ILS., Meinb. Na(. Inst, of France. Vice CAoJrmon— JOHN WOOD, Esq. Tretuurer-WILLIAM TOOKE, Esq., F.R.S. W. Allen, Esq., F.R. & R.A.S. Capt. Beaufort, R.N., F.R. & R.A.S., Hydrographer tothe Admiralty. Francis Boott, M.D. G. Burrows, M.D. Peter Stafford Carey, Esq. A.M. William Coulson. Esq. R. D. Craig, Esq. J. F. Davis, Esq., F.R.S. H.T. Dela BecTie, Esq., F.R.S. The Right Hon. Lord Denman. Samuel Duckworth, Esq.,M.H. B. F. Duppa, Esq. The Right Rev. the Bishop of Durham, D.D. Sir Henry Ellis, Prin. Lib. Brit. Mus. T.F.Ellis, Esq., A.M., F.R.A-S. John EUiotson, M.D., F.R.S. George Evans, Esq., M.P. Thomas Falconer, Esq. I. L. Goldsmid, Esq., F.R. and R.A.S. Francis Henry Goldsmid, Esq. B. Gorapertz, Esq., F.R. and G. B. Greenough, Esq., F.R. and L.S. M. D. Hill, Esq. 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INSECT TRANSFORMATIONS. LONDON: CHARLES KNIGHT & CO., LUDGATE STREET. MDCCCXXXVIII. LONDON : XViuted by William Clowes and Sons, Stamford Street. I UBB CONTENTS. SECTION I.— EGGS OF INSECTS. CHAPTER I.— Intkoductory. Page All insects come from eggs 1 Curious experiment of Kircher ...... 2 Virjjil's receipt for making a swarm of bees ... 3 Origin of these ancient errors 4 Bees in Samson's lion accounted for .... T Fancies of Robinet and Darwin ...... 9 Theory of spontaneous generation 10 Popular errors respecting blight . , . . . .11 Dr. Good's account of blight 12 No insect eggs float in the air 14 Specific gravity of insect eggs 15 Theoretical accounts of honey-dew ..... 16 Accounted for by experiments ...... 18 Instantaneous appearance of insects ..... 19 Tlie " worm i' the bud " traced to its egg .... 20 Insectiferous winds ........ 22 Supposed showers of frogs, snails, &c 23 Diffusion of the seeds of plants ....•« 24 Insects jet out their eggs from fear 25 Origin of mosses on walls 27 Origin of mould in the heart of an apple .... 30 CHAPTER II. Physiology of insects' eggs 33 Theory of colours meant for concealment . . . , ib. Disproved in the case of the eggs of birds .... 34 Illustrated from insect eggs ....... 35 Cause of the colours in eggs 36 Structure of insects' eggs ....... 38 Eggs of ants, spiders, and glow-worms .... 39 Form of insect eggs , . 40 Cause of the oval form in birds' eggs .... 41 Sculpture of the eggs of insects ib. Curious appendages to eggs 43 Eggs with foot-stalks • ^^ Number of insect eggs, and their fecundity, compared with other animals ....... 46 a3 VI CONTENTS. CHAPTER III. Maternal care of insects respecting their eggs . Instanced in a carpenter-bee (jChelustomd) Ichneumons compared to the cuckoo . Proceedings of a solitary bee (Halictus) , , Stratagems of a solitary \Nasp (Cerceris) . . Ovipositor of an ichneumon (Fiinpla) . , Experiments of Reaumur . . . . . Common mistakes of Naturalists Parasite of the cabbage-caterpillar {Pontia) . Egg parasites .... ... Parasites of the aphides Singular parasite of the cockroach . . . Rare parasites of bees and wasps . . . . Tact of insects in discovering food for their young Sometimes select exotic plants . . . . Instanced in a leaf-miner (TepAnti's?) Solitary and gregarious caterpillars Life-boat of eggs constructed by the gnat . Experiments upon it . . . • . . Infallibility of instinct questioned . Mistakes of instinct CHAPTER IV. Hybernation of insects' eggs Proceedings of the gypsey moth compared to the eider-duck Singular groups of eggs ... Protection of eggs from heat Anal tweezers of moths . Eggs in spiral groups .... Arched form of the lackey-moth's eggs Hybernation of the eggs of aphides Singular protection of the eggs of cocci Coccus of the hawthorn Shell-formed coccus of the currant . Hybernation of spiders' eggs Curious spiders' nests tlggs of the vapourer-moth on its cocoon Effects of cold on insects' eggs . Observations of John Hunter Insects not killed by severe frosts CHAPTER V. Hatching of insect eggs .... Structure of the eggs of birds Insects do not hatch their eggs . Anomalous instance of the earwig. Earwigs cannot get into the brain Partial hatcliing by spiders . Experiments upon the wolf-spider by Swammerdam Bonnet ..... Eggs hatched before they are laid Ovo-viviparous insects . Coil of larvaj in the body of a hlow-flv Aphides sometimes produce eggs, sometimes yonn Care taken of these eggs by ants and CONTENTS. Vll Cocco-viviparous flies {HippohoscidcB) Effects of heat upon eggs .... Management of silk- worms' eggs , Eff"ects of light on eggs .... Some insect eggs increase in size . Growth of the eggs of ants .... Development of the eggs of spiders . Spiders live long without food . . , Insects probably gnaw through their egg-shells Valves of insect eggs ..... Period of hatching influenced by temperature SECTION II.— LARV^. Page 116 118 120 ib. 121 122 123 124 125 126 127 CHAPTER VI. Structure of caterpillars, grubs, and maggots 128 Meanings of these terms ..... Note, ib. Supposed transmutation of plants into animals . . . 129 Observations of Un^'er upon this 130 Remarks of Bory St. Vincent 131 Supposed formative power of the blood .... 132 Embryo butterfly in the caterpillar 133 Experiments to show this 134 Dissections of the buds of plants , . . . . .136 Diff"erence of plants from insects ..... 137 Internal structure of caterpillars 138 Breathing-tubes and formation of their blood . . . 139 Colours of caterpillars not intended for concealment . . 140 Imitative forms of caterpillars 142 Walking-leaf insect ........ 144 Caterpillars in form of branches 145 Conspicuously-coloured caterpillars ..... 147 Butterflies supposed to be coloured like flowers . . . 149 Singular forms of caterpillars 151 Forms of water-grubs ....... 154 Breathing-organs in water larvae 156 Water-worms (iWfi.s) may be mistaken for larvae . . 159 Syringe for respiratiota in a water larva .... 161 Curious mask of the same larva . . , , . 163 Dust mask of the wolf-bug (BedKUfMs) 165 CHAPTER VII. Growth, moulting, strength, defence, and hybernation of larvae . 166 Progressive iucrease of the silk-worm . . . . .167 Compared with the growth of buds ..... 168 Process of moulting or casting the skin ..... 169 Accidents interrupt this process 170 Reds, a disorder similar lo renal gravel .... 172 Position of the hairs in moulting 173 Casting of the interior lining of the stomach, &c. . . . 174 Moulting of birds 176 Cast sivius sometimes devoured ...... 177 Misstatement of Goldsmith ...... ib. Contrivances for escape from confinement .... 178 Muscular strength of insects .....' 17^ CONTENTS. Paire Fleas made to draw miniature coaches . . , , 180 Numerous muscles of the C0SSU3 182 Its wonderful strength 1 84 Misstatements respecting the strength of insects . . . 185 Means of escape by spinning ...... 1S6 Defensive hairs and spines of caterpillars .... 187 Excrementitious covering of some lar\'ae .... 190 Origin of the froth on plants called cuckoo-spit ... 191 Winter covering of caterpillars 192 Fat a probable defence against cold 195 CHAPTER VIII. Voracity of caterpillars, grubs, and maggots .... 196 Increase of weight in the silk-worm in thirty days . . 197 Remarkable change in the capacity of the stomach . . 198 Instances of human voracity ...... 201 Jaws or mandibles of larvae 202 Caterpillars ib. Blight caused by an oak-leaf roller ..... 203 Ravages of the buff-tip 204 Encamping caterpillars of the ermine-moth . . . 205 Experiments with these i . . .... . 206 Extraordinary ravages of the brown-tail moth . . . 208 Strange enactment of the Parliament of Paris . . . 209 Cause of the abundance of caterpillars in particular years . 210 Alarm caused in France by the gamma-moth . . .211 Calculation of their fecundity 212 Cabbage-caterpillars prefer weeds ..... 213 Disappearance of the black-veined white butterfly . . 214 Ravages of the caterpillar of the gooseberry saw-fly . . 215 Similar ravages committed on other trees .... 216 Slug-worm of North America ...... 217 Turnip-fly erroneously fancied to come across the sea to Norfolk 218 Effects of jEgeriae on currant and poplar trees . . . 220 Destruction of grain by Kuplocami and Tineae . . . 221 Bee-hives injured by Gallariae 222 Caterpillar which feeds on chocolate 224 CHAPTER IX. Voracity of grubs "... 225 Grub of the cockchafer or may-biig 226 Accountof its transformation, &c '227 Methods of destroying 228 Wire-worm the grub of Hemirhipus 2l'9 Probable mistake respecting the destruction of wheat . . 231 Pea-beetle of North America 2:^3 Corn-weevil ......... 234 Meal-worm, the grub of Tenebrio molitor .... ib. Tabby-moth caterpillar devours butter and fat . . . 236 Intestinal worms ib. Mistakes of Linnaeus, Dr. Barry, and Dr. J. P. Frank . . 237 Experiment of M. Deslonchamps ..... 238 Extraordi^iary case of Mary Riordan, by Dr. Pickells . . 239 Authenticity of this case proved . . . ' . . 241 Fruit-grubs " 242 Nut-weevil and its transformations ib. CONTENTS. Apple-bud weevil . . . . Voracity of Calosoma . Rayed galleries of a bark-grub. Ravages of locusts , Tlieir swarms in Southern Africa The Italian locust Migrations in Palestine and Europe . CHAPTER X. Voracity of maggots Maggots of crane-flies popularly called the grub Remarkable ovipositor .... Destruction of herbage on Blackheath • Similar devastations in Poitou and Holderness Wheat-fly, described by Mr. Shireff Additional particulars by Mr. Gorrie , Observations of Kirby .... Mistake of Mr. Markwick. Hessian-fly, described by Mr. Say , Cheese-hopper the maggot of Piophila Wonderful structure of this maggot Its transformation into a fly . . . Origin of the house-fly (^Musca dumestica) Mistakes of Ray and Reaumur . Voracity of the maggots of blow-flies . Instance of a man devoured by them. Popular mistake respecting lady-birds Their transformations traced to the egg Aphides checked by these and by Syrphidae SECTION III.— PUP^. CHAPTER XI. MechaiMsm of suspending chrysalides Proceedings of larvae upon their approacKing change In what manner some caterpillars suspend themselves Tlieir attempts sometimes unsuccessful Organ for holding fast .... Suspensory cincture of other caterpillars Method of forming this by the swallow-tail Parchment-like pupa-case of flies (^Muscidce) Flask-shaped pupae of Syrphida; Trausformations of a Tipulidan gnat Mode by which the nymph is suspended . Hooked aquatic pupa {Hydrucampa f) CHAPTER XII. Page 2^3 244 245 246 247 249 250 252 ib. 253 254 255 256 259 260 261 262 263 267 268 ib. 269 270 271 273 274 277 278 279 281 282 287 Form and structure of pupae ...... The term metamorphosis objected to . . . Harvey's fancies about transmutation . . . Similar fancies of Goedart exposed by Swammerdam Structure of the pupa of the chameleon-fly. Pupa of the lappit-moth ..... Chrysalis and transformations of the peacock -butterfly Origin of philosophic errors .... Changes produced on pupae by evaporation ib. 289 290 292 293 294 296 297 CONTENTS. Page Objections to the tlieory of evaporation .... 298 Respiratory organs of pupae ...... 300 Experiments upon the breathing of pupae . . . , 301 Valves of the spiracles 302 Breathing apparatus in the pupae of aquatic crane-flies and gnats 304 Plumed apparatus of the blood-worm 305 CHAPTER XT 1 1. Transformation of pupae into perfect insects Theory of transpiration by means of heat . Objections to this theory Experiments by Reaumur. .... Chrysalides hatched under a hen .... Forcing of butterflies in winter .... Retarding tlie evolution of butterflies by cold. Experiments on pupae led to the varnishing of eggs Illustrations of torpidity in animals and plants Various periods of disclosure in the same brood. Supposed final cause of this ..... Fixed time of the day for some insects to be evolved Remarkable evolution of the gnat .... Still more remarkable instance of the blood-worm Netted doors in the pujia cases of caddis-flies . Bellows apparatus in the pupa of the blow-fly . Contrivance in the pupae of wood feeders . . Singularity in the locust-moth Ingenious contrivance in a small leaf-roller Mistake of Bonnet with respect to the teazle-moth Pupa cases opened by extraneous assistance . Observations on this by the younger Huber Experiment by Dr. J. R. Johnson .... De Geer's observations contrary to those of Swammerdam Remarkable circumstance in the hive bee 307 ib. 310 311 312 ib. 313 314 315 316 317 319 320 321 322 323 324 325 326 327 329 330 331 SECTION IV. PERFECT INSECTS. CHAPTER XIV. Expansion of the body and wings in insects newly transformed Structure of birds to contain air .... 333 ib. Expansion in the fly of the ant-lion . . ' . . 'Si4 The mandibles prove it carnivorous .... 335 Transformations of dragon -flies 336 Folded wings of some two-wiuged flies .... 338 [ Mali>ighi's account of the transformations of the silk- worm . 339 Impulsion of fluids into the wings ..... 341 Kirby's account of the expansion of the swallow-tailed butterfly342 Swammerdam's account of the wings of the bee . . 343 Air-tubes in insects' wings. .... . . 344 Nervures in the wings of plumed moths .... 345 Perfect insects do not increase in size, .... 347 Imperfect insects from fallen chrysalides . . . 349 Discharges from newly-evolved insects .... 350 Supposed showers of blood accounted for ... 351 CONTENTS. XI Theories devised to account for crimson snow . Curious fact explaining this, by Mr. T. Nicholson Does not explain the red snow of the Alps. CHAPTER XV. Peculiar motions of insects Motion indispensable to life .... Anecdote of a water-measurer . Mode of combing themselves used by spiders . Oscillatory motions of some tipulidae. Vibratory motions of syr][ihi on the wing. Similar motions of hawks, red-breast, &c. . Experiment on Scioptera vihrans . . . Ilhistrated by the wag-tail, &c.. Gnat dauces in winter ..... Opinion of Wordsworth and others Similar aerial dances of rooks Night gambols of Corethrce? on a book Circular movements of a summer fly . . Sportive movements not necessarily social . Account of the whirlwig, by Kirby and by Knapp Remarkable structure of its eyes Battles of butterflies .... Choral assemblies of ephemeridae . • Account of these by Reaumur Sports of ants ...,., Gymnastics of ants, according to Huber . Page 352 354 355 356 ib. 357 358 359 360 361 362 363 ib. 364 ib. 365 366 367 368 370 371 373 ib. 376 377 CHAPTER XVI. Peculiar locomotions of insects ....... 379 Examples from quadrupeds ...... ib. Singular movements of some plant-bugs .... 380 trailing of the whirlwig beetle. ..... 381 Walking on water by spiders, &c 382 Walking through water by aquatic mites • . . 383 Oblique pace of midges ....... 384 Insect with its legs on its back ..... 385 Rapid galloping of the strawberry-mite .... 386 Slow movements of the oil-beetles 387 Supposed sponges in the foot of the fly . . . . 388 Correct notions of Derham and White, proved by Sir E. Home 389 Apparatus in the feet of flies 390 Leaping muscles of the flea ...... 392 Leaping of grasshoppers and springtails .... 393 Springing of spiders on their prey 394 Flight of insects .395 Mechanism of insects' wings and their muscles, according to M. Chabrier 396 Flying of spiders without wings 397 CHAPTER XVn. Rest of insects 399 Night insects rest in the day ib. xu CONTENTS. Day movements of other insects . . . . . Insects have no brain, nor spinal cord Want also a proper heaii; as well as blood Supposed pulse in insects No circulation Alleged discovery of an insect circulation, by Dr. Cams How the circulation is effected in the sleep of man . The same effects cannot take place in insects Sleep of senses not equally profound . . . . Torpidity of insects in winter Hybernation of ants ....... Anecdotes from Huber ...... Hybernation of bees Discrepancies of opinion among naturalists Hybernation of the hearth-cricket Page •100 ib. 401 ib. 402 ib. 404 405 406 ib. 407 408 410 413 414 INSECT TRANSFORMATIONS. SECTION I.— EGGS OF INSECTS Chapter I. All Insects come from Eggs as Plants do fr.om Seeds. — Vnlt;ar errors of Insects being generated by Putrefaction and Blighting Winds dis proved by experiment. It was universally believed by the ancient philoso- pliers, that maj^gots, flies, and other insects were generated from putrefying substances. This opinion continues to be held by uninformed persons among ourselves; — though it would be equally correct to maintain, that a flight of vultures had been generated by the dead carcass which they may be seen devouring, or a flock of sheep from the grass-field in which they graze. Another opinion, perhaps still more generally diffused, is, that caterpillars, aphides, and other garden insects which destroy the leaves of plants, are gene- rated, propagated, or, at least, spread about, by certain winds or states of the air, mysteriously and inde- finitely termed blight. The latter belief is, probably, not so easy of immediate refutation as the former; — but, as we shall endeavour to show, it seems to us to be equally erroneous. The small size of insects renders it somewhat easy to pass oif fanciful opinions regarding them, since it is diflkult for common observers to detect mistakes ; B 2 INSECT TRANSFORMATIONS, but similar notions have been entertained by writers of no mean reputation, respecting even the larger animals. The celebrated Kircher, for example, one of the most learned men of the seventeenth century, goes so far as to give the following singular recipe for the manufacture of snakes : — " Take some snakes," says he, '* of whatever kind 3»ou want, roast them, and cut them in small pieces, and sow those pieces in an oleaginous soil ; then, from day to day, sprinkle them lightly with water from a watering-pot, taking care tliat the piece of ground be exposed to the spring sun, and in eight days you will see the earth strewn with little worms, which, being nourished with milk diluted with water, will gradually increase in size till they take the form of perfect serpents. This," he subjoins with great simplicity, " I learned from having found in the country the carcase of a serpent covered with worms, some small, others larger, and others again that had evidently taken the form of serpents. It was still more marvellous to remark, that among these little snakes, and mixed as it were with them, were certain flies, which I should take to be engen- dered from that substance which constituted the aliment of the snakes*." Kircher's more shrewd and less fanciful cor- respondent, Redi, determined to prove this singular recipe before he trusted to the authority of his friend. " Moved,'' he says, " by the authentic testimony of this most learned writer, I have frequently tried the experiment, but I could never witness the genera- tion of those blessed snakelets made to handf." But though Redi could not, in this way, produce a brood of snakes, his experiments furnished an abundant progeny of maggots, — the same, unques- * Athan. Kircher, Mund. Subterran. lib. xii. f Redi, Generat. Xnsectorum, ed>t. Axnstel, 1686. GENERATION OF INSECTS. 3 tioiiably, that the imagination of Kircher had mag- nified into young snakes, — which, being confined in a covered box, were in a short time transformed into flies, at first of a dull ash colour, wrinkled, unfinished, and their wings not yet unfolded, — as is always the case with winged insects just escaped from their pupa case. In less than an hour, however, they "un- folded their wings and changed into a vivid green, marveKously brilliant" — most probably the green flesh-fly (Mil sea CfBsar. Linn.) It is a common opinion in this country, particu- larly in the north, that if a horse's hair be put into the water of a spring or a ditch, it will be in process of time transformed, first into a hair-worm, and afterwards into an eel. The deception, as in the instance of Kircher's snakes, arises from the close resemblance between a hair and the hair-worm {Gordius aquaticus, Linn.), and between this and a young eel. This fabled transformation of hair, which we have heard maintained even by several persons of good education, is physically impossible and absurd. The method laid down by Virgil in his Georgics for generating a swarm of bees is precisely of the same description as the snake recipe of Kircher; and though the " Episode of Aristseus recovering his bees" has been pronounced to be " perhaps the finest piece of poetry in the world," we must be per- mitted to say that it is quite fabulous and unphiloso- phical* The passage runs thus : — Oft from putrid gore of cattle slain Bees have been bred. * * * ^ narrow place, And for that use contracted, first they choose, Then more contract it, in a narrower room, Wall'd round, and cover'd with a low built roof. And add four windows, of a slanting light From the four winds. A bullock then is sought, His horns just bending in their second year ; b2 4 INSECT TRANSFORMATIONS. Him, much reluctant, with o'evpow'ring force. They bind ; his mouth and nostrils stop, and all The avenues of respiration close ; And buffet him to death : his hide no wound Receives ; his batter'd entrails burst within. Thus spent they leave him ; and beneath his sides Lay shreds of boughs, fresh lavender and thyme. This, when soft zephyr's breeze first curls the wave, And prattling swallows hang their nests onliigh. Meanwhile the juices in the tender bones Heated ferment ; and, wondrous to heholdy Small aniniiils, in clusters, thick are seen, Short of their legs at first : on filmy wings, Humming, at length they rise ; and more and more Fan the thin air ; 'till, numberless as drops Pour'd down in rain from summer clouds, they fly. Trapp's Virgil, Georg. iv. 369. Columella, a Roman writer on rural affairs, after directing- in what manner honey is to be taken from a hive by killing; the bees, says, that if the dead bees be kept till spring, and then exposed to the sun among the ashes of the fig-tree, properly pulverised, they may be restored to life. These fancies have evidently originated from mis- taking; certain species of flies (Syrphi, Bombylii, &c.) for bees, which, indeed, they much resemble in general appearance ; though they have only two wing?, and short antenna?, while all bees have four wings, and long antennae. Neither the flies nor the Comparative figures of a bee (a) and a syrphus (6). bees are produced by putrefaction ; — but as the flies are found about animal bodies in a state of decom- position, the ancients fell into an error which accurate observation alone could explode. The maggots of GENERATION OF INSECTS. 5 blow-flies, as Swammerdam remarks, so often founil ill the carcasses of animals in summer, "some- what resemble those produced by the egc^s of bees. However ridiculous,'' lie adds, " the opinion must appear, many great men have not been ashamed to adopt and defend it. The industrious Goedart has ventured to ascribe tlie origin of bees to certain dunghill worms *, and the learned De Mei joins with him in this opinion ; though neither of them had any observation to ground their belief upon, but that of the external resemblance between bees and certain kinds of flies {Syrphidce) produced from those worms. The mistake of such authors should teach us," he continues, " to use great caution in our determinations concerning things which we have not thoroughly examined, or at least to describe them with all the circumstances observable in them. Therefore, although this opi- nion of bees issuing from the carcasses of some othet animals by the power of putrefaction, or by a trans- position of parts, be altogether absurd, it has had, notwithstanding, many followers, who must have in a manner shut their eyes in order to embrace it. But whoever will attentively consider how many requi- sites there are for the due hatching of the bee's egg, and for its subsistence in the grub state, cannot be at a loss for a clue to deliver himself out of that laby- rinth of idle fancies and unsupported fables, which, entangled with one another like a Gordian knot have even to this day obscured the beautiful simplicity of this part of natural history f." Redi was by no means satisfied with the first results of his experiments upon the flesh of snakes, for several * The maggots of Eristalis tenax, Famsi. E. api/ormis, Mkiokn, and other Syrphidcr, well known in common sewers by their long tails, like those of rats. f Swammerd. Book of Nature, i. 228. 11 3 6 INSECT TRANSFORMATIONS, species of flies were produced, giviiin; some coun- tenance to the opinion of Aristotle, Pliny, Mouffet, and others, that different flesh engenders different flies, inheriting the disposition of the animal they are bred from. He accordingly tried almost every species of flesh, fish, and fowl, both raw and cooked, and soon discovered (as he could not fail to do) that the same maggots and flies were produced indis- criminately in all. This ultimately led him to ascertain that no maggots are ever generated except from eggs laid by the parent flies: for when he carefully covered up pieces oi meat with silk or paper sealed down with wax, no maggots were seen; but the parent flies, attracted by the smell of the covered meat, not unfrequently laid their eggs on the outside of the paper oi silk, the maggots hatched from these dying, of course, for want of nourishment. With respect to bees, it becomes even more absurd to refer their generation to putrefaction, when we consider that they uniformly manifest a peculiar antipathy to dead carcasses. This was remarked so long ago as the time of Aristotle and of Pliny*; and Varro asserts that bees never alight upon an unclean place, nor upon anything which emits an unpleasant smell. This is strikingly exemplified in their carrying out of the hive the bodies of their companions who chance to die there ; and in their covering over with propolis the bodies of snails, mice t, and other small animals which they cannot remove J. These facts, which are unquestionable, may at first view appear to contradict the Scripture history * Aristotle, Hist. Animal, ix. 40. Pliny says, " Omnes carue cscuiitur, contra quam apes, quae nullum corpus attinguut." f Iluish on Bees, p. 100. I Insect Architecture, p. 109, GENERATION OF INSECTS. 7 of Samson, who, havinp; killed a young lion in the vineyards ofTimnath, "after a time turned aside to see the carcass of the Hon : and behold a swarm of bees and honey in the carcass*.'* It only requires us, however, to examine the facts, to show that this does not disagree with the preceding statement. Bochart, in his Sacred Zoology, tells us that the word rendered "carcass" literally signifies skeleton ; and the Syriac version still more strongly renders it a dried body (corpus exsiccatum). Bochart fur- ther contends, that the phrase *' after a time " is one of the commonest Hebraisms for a year. But when we consider the rapid desiccation caused by the sum- mer suns of Palestine, this extension of time will be unnecessary; for travellers tell us that the bodies of dead camels become quite parched there in a few days. We have the testimony of Herodotus, that a swarm of bees built their cells and made honey in the dried carcass of a man placed above the gate of Athamanta. Soranus also tells us of a swarm of bees found in the tomb of the celebrated Hippocrates. " I have been told," says Redi, " by Albergotto, a man of profound erudition, that he had seen a swarm in the cranium of a horse. Bees," he adds, " not only do not Hve upon dead bodies, but they will not even come near them, as I have often proved by ex- periment." " It is probable," says Swammerdam, " that the not rightly understanding Samson's ad- venture of the lion gave rise to the popular opinion of bees springing from dead lions, oxen, and horses.'' Kirby and Spence seem disposed to consider Samson's bees, as we have done those of Virgil, to be flies resembUng bees; but the " honey " which Sauison " took in his hands and went on eating," is fatal to such an exposition. The ancients had another fancy respecting the * Judges xiv. 8. B INSECT TRANSFORMATIONS. propaga on of bees, equally absurd, though much more poetical. Virgil tells us that. From herbs and fragrant flowers, with their mouths They cull their young. Georg. iv. Aristotle* had long before stated, and De Monfort in modern times repeated the assertion t, that the olive, the cerinthus, and some other plants, have the property of generating young bees from their purest juices. We may well say, with Lactantius, that *' they make shipwreck of their wisdom, who adopt without judgment the opinions of their ancestors, and allow themselves to be led by others like a flock of sheep |.". Modern naturalists, being accustomed to minute accuracy in their observations, can both disprove and readily explain most of those erroneous fancies, by tracing the causes which led, and may still lead, inaccurate observers into such mistakes. It would have been well if such unfounded fancies had rested here ; but philosophical theorists, both of ancient and modern times, have promulgated dreams much more extravagant. The ancients taught that the newly-formed earth (hatched as some said from an Q^'g) clothed itself with a green down like that on young birds, and soon after men began to sprout up from the ground as we now see mushrooms do. The refined Athenians were so firmly convinced of their having originally sprung up in this manner, that they called themselves " Earth-born " (Erich- ihojiii), and wore golden tree-hoppers (^Cicadce) in their hair, erroneously supposing these insects to have a common origin with themselves §. Lucretius * Hist. Animal, v. 22. f Le Portrait de la Mouche a Miel. Liege, 1646. X Divin. Instit. ii. 7 ; in Redi's motto. Shepherds on the continent lead their sheep, as those of Israel did. See Mena- geries, vol. i. p. 81. § The Cicada; do not deposit their eggs in the earth, but on lices, &c. See Insict Arcbitcctitre, cliap. vii. GENERATION OF INSECTS. 9 affirms, that even in his time, when the earth was supposed to be growing too old to be reproductive, " many animals were concreted out ot" mud by showers and sunshine*." But the ancients, it would appear, had the shrewdness seldom to venture upon illustrations of their philosophical romances by particular examples. This was reserved for the more reckless theory- builders of our own times. We find Robinet, for example, asserting that, as it was nature's chief object to make man, she began her " apprentissage," as he calls it, by forming minerals resembling the single organs of the human body, such as the brain in the fossil called Brain-stone {Meandrina cerebri- formh, ParkinsonI). Darwin, again, taking the hint from Epicurus, dreams that animals arose from a single filament or threadlet of matter, which, by its efforts to procure nourishment, lengthened out parts of its body into arms and other members. For example, after this filament had improved itself into an oyster, and been by chance left dry by the ebbing of the tide, its efforts to reach the water again expanded the parts nearest to the sea into arms and legs. If it tried to rise from its native rocks, the efforts produced wings, and it became an insect, which in due course of time improved itself by fresh efforts till it became a bird, the more perfect members being always hereditarily transmitted to the progeny. The ditlerent forms of the bills of birds, whether hooked, broad, or long, were, he says, gradually acquired by the perpetual endeavours of the creatures to supply their wants. The long-legged water- * Multaque nunc etiam existunt animaVia terris, Imbribus et calido soils concreta vapore. De Nat. Rer. v. 795. f Robinet, Consid. Philosophiques dc la Gradation Naturelle des Formes de TEtre. Paris, 1768. lO INSECT TRANSFORMATIONS. fowl {Grallatores^ Vigors) in this way acquired length of legs sufficient to elevate their bodies above the water in which they waded. " A proboscis," he says, " of admirable structure has thus been acquired by the bee, the moth, and the humming--bird, for the purpose of plundering- the nectaries of flowers*." Lamarck, an eminent French naturalist, recently de- ceased, adopted the same visions ; and, among other illustrations of a similar cast, he tells us that the giraffe acquired its long neck by its effects to browse on the high branches of trees, which, after the lapse of a few thousand years, it successfully accomplished. Theories like the preceding all originate in the en- deavours of human ingenuity to trace the operations of nature (iirther than ascertained facts will warrant ; and the necessary blanks in such a system, which presupposes much that cannot be explained, are filled up by the imagination. This inability to trace the origin of minute plants and insects led to the doctrine of what is called spontaneous or equivocal generation, of which the fancies above- mentioned are some of the prominent branches. The exjieriments of Redi on the hatching of insects from eggs, which were published at Florence in 1668, first brought discredit upon this doctrine, though it had always a few eminent disc pies. At present it is maintained by a considerable number of distinguished naturalists, such as Blumenbach, Cuvier, Hory de St. Vincent, R. Brown, &c. "The notion of spontaneous generation," says Bory, " is al first revolting to a rational mind, but it is, not- withstanding, demonstrable by the microscope. The fact is averred: Midler has seen it, I have seen it, and twenty other observers have seen it : the pan- durinia exhibit it every instant t-" These pandorinia ♦ Darwin' Zoonomia, sect, xxxix. 3id edit. London, 1801. f Diet. Classi(iue d' Hist. Nat., Art. Microscopiques, p. 541. GENERATION OF INSECTS. II he elsewhere describes as probably nothini? more than "animated scions of Zoocarpse " (propagules animes des Zoocarpes).* It would be unprofitable to g:o into any lengthened -discussion upon this mysterious subject; and we have great doubts whether the ocular demonstration by the microscope would succeed except in the hands of a disciple of the school. Even with naturalists, whose business it is to deal with facts, the reason is often wonderfully influenced by the imagination. But the question immediately before us happily does not involve these recondite discussions ; for if even pandorinia and other animalcules were proved bfyond a doubt to originate in the play of chemical affinities or galvanic actions — (a more refined pro- cess, it must be confessed, than Kircher's chopped snakes), it would not affect our doctrine that all insects are hatched from eggs : for no naturalist of the present day classes such animalcules among insects. Leaving animalcules and zoophytes, there- fore, out of the question, we have only to examine such branches of the theory of spontaneous genera- tion as seem to involve the propagation of genuine insects, — like the fancies about putrefaction which we have seen refuted. The notion that small insects, such as aphides and the leaf-rolling caterpillars, are spread about, or rather generated, by what is termed blight (possibly from the Belgic blijikan, to strike with lightning), is almost universally believed even by the most intelligent, if they have not particularly studied the habits of insects. Mr. Main, of Chelsea, an ingenious and well-informed gardener and naturalist, describes this as an " easterly wind, attended by a blue mist. The latter is called a blight, and many people imagine that the aphides are wafted through tlie * Diet. Class, Art. Pandoriuoes. 12 INSECT TRANSFORMATIONS. air by this same mist*." *' The farmer," says Keith, *' supposes these insects are wafted to him oil the east wind, while they are only generated in the extravasated juices as forming a proper nidus for their eggst." A more detailed account, however, is given by the late Dr. Mason Good, and as he speaks in part from personal observation, and was not only one of the most learned men of his time, but an excellent general naturalist, his testimony merits every attention • — " That the atmosphere," says Dr. Good, " is freighted with myriads of insect eggs that elude our senses, and that such eggs, when they meet with a proper bed, are hatched in a few hours into a perfect form, is clear to any one who has attended to the rapid and wonderful effects of what, in common lan- guage, is called a blight upon plantations and gar- dens. I have seen, as probably many who read this work have also, a hop-ground completely overrun and desolated by the aphis hmmili, or hop green- louse, within twelve hours after a honey-dew (which is a peculiar haze or mist loaded with poisonous miasm) has slowly swept through the plantation, and stimulated the leaves of the hop to the morbid secretion of a saccharine and viscid juice, which, while it destroys the young shoots by exhaustion, renders them a favourite resort tor this insect, and a cherishing nidus for myriads of little dots that are its eggs. The latter are hatched within eight-and-forty hours afier their deposit, and succeeded by hosts of other eggs of the same kind; or, if the blight take place in an early part of the autumn, by hosts of the young insects produced viviparously ; tor, in ditferent seasons of the year, the aphis breeds both ways. Now it is highly probable that there are minute * Loudon's Ma jr. of Nat. Hist. i. 180. + Keith's Physiological Botany, ji. 486. GENERATION OF INS-ECTS. 13 efygs, or ovula, of innumerable kinds of animalcules floating by myriads of myriads through the atmo- sphere, so diminutive as to bear no larger proportion to the eggs of the aphis than these bear to those of the wren or the hedge-sparrow ; protected at the same time from destruction, by the filmy integument that surrounds them, till they can meet with a proper nest for their reception, and a proper stimulating power to quicken them into life ; and which, with respect to many of them, are only found obvious to the senses in different descriptions of animal fluids*." It appears to us that it can be nothing more than a fancy, which is quite unsupported by evidence, to say that the eggs of any species of animalcules or insects float about in the atmosphere; for, inde- pendent of their weight, (every known sjiecies being greatly heavier than air,) the parent insects of every species whose history has been accurately investi- gated, manifest the utmost anxiety to deposit their eggs upon or near the appropriate food of the young. To commit them to the winds would be a complete dereliction of this invariable law of insect economy. But admitting for a moment this hypothesis, that the eggs of insects are diffused through the atmosphere, the circumstance must be accompanied with two conditions, — the eggs must either be dropped by the parents while on the wing, or be carried off by winds from the terrestrial substances upon which they may have been deposited. On the supposition that the eggs are dropped by the mother insects while on the wing, we must also admit (for there is no avoiding it) that they continue to ; i float about, unhatched, from the end of summer I I till the commencement of spring, at which time only ,, i the broods make t.ljeir appearance. Yet when we " * Good's Study of Medicine- vol, i , p. 339, Srd edition, Lon- don, 18^3. C 14 INSECT TRANSFORMATIONS. -Consider the rains, snows, and winds, to which they must be exposed for six or nine months, we think the hardiest theorist would scarcely maintain that a single egg could out-weather these vicissitudes, and continue to float in the air. It may not be out of place to remark, that the female aphides, which de- posit eggs in autumn, have no wings. Again, on the supposition that the eggs are de- posited on plants, trees, or other objects, it is still more unlikely that they could be carried into the air ; for, on exclusion, they are, with very few exceptions*, enveloi)ed in an adhesive cement wliich glues them to the spot on which they are deposited. When eggs are deposited singly, this cement usually enve- lopes each with a thin coating, as in the instance of the admirable butterfly {Vanessa Atalanta) ; but when they are placed in a group the cement is sometimes spread over the whole, as in the instance of the white sain moth (^Leucoma salicis, Ste- phens). This cement is evidently intended by Nature (who seldom accommodates her plans to our theories) to prevent the eggs from being carried from the place selected by the mother insect for their deposition. Those eggs, therefore, which are placed on the outside of substances, have this provision for their secure attachment to the locality chosen by the instinct of the mother. But, on the contrary, the principle does not always hold in the case of those deposited in nests and excavations, and particularly as to those of ants and termites. The working ants, in- ' deed, carry the eggs from the top to the bottom of their galleries, according as the weather is favourable or unfavourable for hatching. The labourers of the white ants (^Tennites) ^ again, attend their queen with the utmost care when she is laying ; for as she can- not then move about, they are under the necessity * Latreille, Hist. Grener. xiv., p. 342. GENERATION OF INSECTS. 15 of carryino: off the eg-g-s, as they are laid, to the nurseries. The extraordinary labour which this re- quires ill the community may be understood, when, according" to Smeathman, she lays 60 eggs in a minute, which will amount to 86,400 in a day, and 31,536,000 in a year. The exceptions now men- tioned, however, do not in the least invalidate on*" general position. Cell of a queen of the Termites bclhcosi, uroKcn open in front , the labourers surrounding thu queen and carrying off her eggs. Another no less remarkable circumstance is the great weight, or specific gravity, of the egg-s of in- sects. From numerous experiments we may venture to say that those of all the species which we have tried sink rapidly in water the moment they are thrown into it, from the egg of the drinker moth {Odonestis Potatoria^ Germar), which is nearly as large as a hemp-seed, to that of the rose-plant louse {Aphis ros(E), which is so small as to be barely visible to the naked eye. Some eggs of the gipsy moth {Ilypogyrnna dispar, Stephens), indeed, floated in water, because they were covered vvith down. It is well known, as we shall presently show, that the dif- fusion of many of the seeds of plants is accomplished by the winged down with which they are clothed ; c2 16 INSECT TUANSFORMATIONS. but the down upon the et^gs of insects does not conduce to this end. Whether insect egi^s be naked or clothed with down, they are invariably, as far as their history has been investigated, deposited close to or upon substances capable of affording food to the young when hatched. In making experiments upon the specific gravity of eggs, it should be remembered that no infertile or unimpregnated egg will sink; for having some hundreds of these laid by dif- ferent species of insects reared in our cabinet, we found, upon trial, that they uniformly floated, while those which we knew to be impregnated as uniformly sunk. A female, for example, of the rose-leaf roller {Lozoticnia Rosana, Stephens) was reared by us, in solitude, under an inverted wine-glass, uj)on the side of which she glued a patch of eggs, of course, unimpregnated ; these, upon trial, all floated in water. But eggs of the same species taken from the outside of a pane of glass close to a rose-tree, all sunk in water ; and it is to be fairly presumed, as the parent of the latter was in a state of freedom, that these were impregnated. We found the same distinction, indeed, to hold in the eggs of the drinker moth, the gipsy moth, and numerous other insects*. Dr. Good's account of " honey dew," which he describes as " a peculiar haze or mist loaded with a poisonous miasm," that stimulates " the leaves of the hop to the morbid secretion of a saccharine and viscid juice" — appears to us unsupported by facts. Lin- naeus t, on the contrary, who was not wedded to the meteorological theory of a miasmatous haze, ascribes the honey-dew on the hop leaves to the caterpillar of the ghost moth {Hepialus hiimuU) attacking the roots. Dr. Withering, favouring this account, re- commends covering the roots with stones as a preveu- * J. R. t Quoted by Keith, Phys, Bot., ii. 143. GENERATION OF INSECTS. 17 live; for the caterpillars, he avers, never attack wild hops which grow in stony places, because they cannot get at the roots*. It appears to us, however, that there can be little doubt that the sweet syrupy coat- ing-, called honey-dew, found on the leaves of the hop, is nothing more than the excrement of the insect {Aphis hunudi) whose propagation we are discussing. •' The honey-dew," says Loudon " mostly" (we be- believe always) " occurs after the crops have been attacked by these insects." f Sir J. E. Smith, who admits this to be the connnon cause of honey-dew, contends tliat what is found on the leaves of the beech is an exception; but he adduces no evidence at all satisfactory in proof of its being caused by unfavour- able winds J ; while the undoubted fact of its being the excrement of aphides in so many other instances § weighs strongly against him. A novel theory of honey-dew has just been pub- lished by Mr. John Murray, who ascribes it to an electric change in the air. " Last summer," he says, " we investigated the phenomenon with great care : the vteather had been parched and sultry ior some weeks previous, and the honey-dew pre- vailed to such an extent, that the leaves of the cur- rant, raspberry, &c., in the gardens, literally distilled from their tips a clear limpid honey-dew, excreted from the plant; lor the phenomenon was observable on those plants that were entirely free from aphides, and so copious vvas it, where these insects were found, that had their numbers been centuple they could not certainly have been the source of the sup- ply. The question with me, however, was set at rest by applying a lens, having previously washed and * Botan, Arrangement, ii., 440, 3r(l ed, Encycl. of Agnculturo, p. 865, s. 5444. X Intioductiun to Botany, p. 189. ( Sec Liuii. Traua. vol. vi. & WiUdtuow, Piuicip. of Botany .p.34o\ c 3 18 INSECT TRANSFORMATIONS. dried the leaf by a sponge, for in this case the imme* diately excreted globules became apparent*." In all observations upon insects, and the other minute parts of creation, it is often exceedingly dif- ficult to distinguish between a cause and an effect. The question of the formation of honey-dew appears to us particularly liable to erroneous conclusions ; and we therefore venture to mention a few circumstances which seem irreconcileable with Mr. Murray's ingenious theory. The hop fly {Aphis humuli) we think, neither does, nor (for want of appropriate or- gans) can, feed on the honey-dew ; and if it did, this feeding would prove rather beneficial than otherwise to the plant, by clearing it from the leaves whose re- spiratory functions it obstructs. So far from feeding on diseased plants, an aphis only selects the youngest and most healthy shoots, into the tender juicy parts of which it thrusts its beak {hausteUum) , which in some species is much longer than the body, and no more fitted for lapping honey-dew than the bill of iEsop's crane was for eating out of a shallow plate. In the experiment, tried by Mr. Murray, of wiping a leaf, might not the leaf have been previously wounded, perhaps, by the beak of some aphis, and hence the exudation of sap, not honey-dew ? and may not the circumstance of his finding the honey- dew on leaves where there were no aphides be accounted for on the principle that the aphides had abandoned, as they always do, the parts covered with their ejecta, unless these fell from insects on some over-hanging branch? It is justly remarked by M. Sauvages, that they are careful to eject the honey-dew to a distance from where they may be feeding, t. We have now in our study a plant of the Cliinese chrysanthemu m {Anthcmis Artemisi?/s\s/, ascertained beyond quesiion that it always consisted of the minute buds of common mosses, such as the wall screw moss {Tortula muralis) and the common hair- hood moss (^Polytrichmn commune)*. At Glasgow, xve have repeatedly remarked, that o!i the walls of houses, built with freestone raised from a quarry more than a hundred feet under the surface of the soil, the whole exterior would, in the course of one month, appear as green as if painted, with these in- numerable germinating' mosses +. The germination of mosses on walls appears to arise from the seeds {sporides) being carried into the air. This process is iacilitated by their extreme mi- nuteness and their comparative lightness, for they do not sink in water like the seeds of phenogamous plants and the eggs of insects, as appears from their germinating on the surface of stagnant water as frequently as on walls. In low situations, the mode in which the seeds of cryptogamic plants are ditfused is well exemjjlitied in tlie puif-ball {Lycoperdon)^ which, when ripe, explodes its sporules in the form of a smoke-like cloud. Mosses again, which grow on trees and walls, if they do not thus explode their sporules, must drop them into the air ; and, as they chiefly ripen early in spring, the winds which then prevail will scatter them to considerable distances. But we omly state this as a highly probable inference from Drunimond's discovery: to detect these all but invisible seeds floating in the atmosphere, and trace them in their passage from the parent plant to the wall or tree where they begin to germinate, we think- is hardly possible. If the doctrine be sound, that every plant arises from seed, we must either believe that iniwimerable * Liiiii. Trans. f J. K DISPERSION OF SEEDS. 29 mosses are wafted to the walls tlirouoh tlie air, or adopt the hypothesis that they have existed for cen- turies in the interior of the rocks of the quarry. That it is not impossible the seeds may have existed in the rocks several curious facts would lead us to believe. Some seeds, for example, retain the power of germi- nating^ for an indefinite length of time; since the wheat usually wrapt up with Egyptian mummies will often germinate and grow, as well as if it had been gathered the preceding harvest. It also bears upon this subject, that when a piece of ground, which has never been tilled, is turned up by the spade or tlie plough, it immediately becomes covered with a crop of annuals, not one of which may grow within many miles of the spot; and a number of them, such as hedge mustard {Hisymhrium officinale) and chick- weed {Aldne media), whose seeds are not winged. It is no less worthy of remark that all these annuals will again disappear as soon as the grass is suffered to spread over the spot which has been dug up. It is mentioned by Mr. James Jennings, in Time's Telescope for 1823, that the coltsfoot (Tussilago farfard) is usually the first plant which appears in England in such cases — a circumstance by no means remarkable, as the seeds of this plant are winged with down, and extremely light. A still more minute family of cryptogamic plants, and consequently more difficult to trace, is well known by the popular name of mould or mouldiness (Mu~ cedines, Linn.) This, Adolpe Brongniart justly remarks, is, in one of its groups, nearly allied to the putf-balls (JLycoperda), whose mode of diffusing their seeds we have just described. When mould is exa- mined by the microscope it is seen to resemble these; and sometimes various fungi are, when mature, filled ■with a blackish dust, suppot^ed to be the seed. MicheU, of Florence, an eminent botanist, resolved ■^3 30 INSECT TRANSFORMATIONS. to try whether this supposed seed would grow if sown on vegetable substances, and found that it did so. On his experiments being; repeated at Bologna, however, it was discovered that the mould grew equally well where none of the black powder had been sown ; but Spallanzani, by more accurate at- tention, confirmed the conclusion of Micheli. He collected a great quantity of the dust, and, taking a number of pieces of moistened bread, apples, pears, gourds, &c., sowed some thickly, others sparingly, and others not at all. The result was, that on the unsown substances the mould did appear, but several days later, and then greatly less in quantity, than on the sown substances ; while of these two, the pieces thickly sown had more than double the quantity of the pieces thinly sown, though, when it came up thick, it did not grow so tall. Blicroscopic views of apple and pear mould. A A, Part of a shrivelled apple, covered with mould on the inside, aaaat several of tlie individual mould plants highly magnified, b, a branched one. c d, seed-vessels, one bursting and scattering its seed, e, one mushroom-shaped. /, a portion of pear mould, of a branched form. We were much struck last autumn (1829), upon cutting an apple asunder, to find in the seed-cells a DISPERSION OF SEEDS. 31- copious growth of the mould with the slender stems and globular heads figured by Spallanzani. Mould upon an apple is not indeed wonderful ; but the one in question was not only large, but apparently sound throughout. Whence, then, came the seeds of this mould in the very core of the apple ? We have also met with mould of a ditferent species, resembling the green mould on the rind of oranges (Acrosporiu?n fasciculatmn, Greville), even on the kernels of nuts, when there was no opening save the minute pores in the shell. Through these pores, then, after being stripped of the husk that covered them, the seed of this nut-mould must have entered. This, however, will not account for the mould in the apple; the seed of which, we think, must have been intro- duced while it was in embryo, in some such way as the seeds of the subcortical fungi so abun«]ant on dead leaves and branches of trees. Th^s again may be illustrated by the curious facts respecting substances found in the interior wood of trees. Sir John Clark, for example, tells us that the horns of a large deer were discovered in the heart of an oak in Whinfield Park, Cumberland, fixed in the timber with large iron cramps, with which, of course, it had at first been fastened on the outside *. The eminent naturalist, Adanson, on visiting Cape Verd, was struck with the venerabie aspect of a tree fifty feet in circumference ; and recollecting having read in some old voyages that an inscription had been made upon such a tree, he was induced to search for this by cutting into the wood, and, marvellous to say, he actually found it under 300 layers of wood t ! De CandoUe, one of the greatest living botanists, remarked " a frost-bitten part in the wood of a tree, cut down in l^OO hi the forest Of 'Fontainebleau. * Phi'l. Trans., vol. xli. p. 448. t Adansou, Voyages Senegal. 32 INSECT TRANSFORMATIONS. This heino- covered with ninety-one layers of wood, indicated that the accident occjirred in 1709, so re- markable for a severe frost*.'* With these facts before us, we think the introduction of the seed of the mould into the centre of the apple by no means so unaccountable as at first view it appeared. Be this as it may, we tried, with the seed g-athered from this apple-mould, similar experiments to those of Spallanzani, with results precisely similar to his ; and being- in this way able at pleasure to produce mould of the same species by sowing, we are entitled to conclude that all moidd arises from seed, other- wise nature must produce the same effect from dis- similar causes, which is contrary to the first principles »»f sound philosophy t- * Coiiv. on Veg. Physiol, i. 59. f J. R» Chapter II. Physiology of Insects' Eggs.— Their Colour, Structure, Shape, Site, and Number. It was a notion of Darwin's (much more ingenious and plan ible than his metamorphoses of shell-fish into birds,) that the variety in the colours of ei>:<;s, as well as the colours of many animals, is adapted to the purposes of concealment from their natural ene- mies. Thus, he says, the snake, the wild cat, and the leopard, are so coloured as to resemble dark leaves and their lighter interstices ; birds resemble the colour of the brown ground or the green hedges which they frequent; while moths and butterflies are coloured like the flowers which they rob of their honey*. By following up this curious theory, Gloger, a German naturalist f, has remarked, that those birds whose eggs are of a bright or conspicuous colour instinctively conceal their nests in the liollows of trees, never quit them except during the night, or sit immediately after they have laid one or two eggs. On the other hand, in the case of birds who build an exposed nest, the colours of the eggs are less at- tractive. Amongst birds w.hose eggs are perfectly white — the most conspicuous of all colours, — he instances the kingfisher (Jlccdo), which builds in a hole in a river's bank; the woodpecker (P/c?/.s), which builds in the hole of a tree; and the swallow {Hirundo domesiica), whose nest has a very small * Zoonomia, Sect. 39, p. 248, Srd ed., and Botan. Gardt'n, note on Rubia. f Verhuiid. der Gesel'lsch. Natiufurhch. Freunde. Berlin, 1824. 3t INSECT TRANSFORMATIONS. opening: while owls and hawks, which scarcely quit Iheir nests in the day, and pig-eons, which only lay one or two eg-g-s and sit immediately after, have also white eggs. The bright-blue, or bright-green egg, again, belongs to birds which build in holes, as the starling {Stiirnus vulgaris), or which construct their nests of green moss, or place them in the midst of grass, but always well covered. Almost all singing birds, he alleges, lay eggs of a dull or dark ground, and variously speckled ; and they for the most part build open nests with materials similar in colour to the eggs, so that no evident contrast is presented which might lead to their discovery and destruc- tion. We may add from Darwin the examples of the hedge-sparrow {Accentor modiilaris)^ whose eggs are greenish-blue, as are those of magpies and crows, which are seen from beneath in wicker nests, between the eye and the blue of the firma- ment*. As this theory is but indirectly connected with our subject, we cannot here spare room to examine it ; but we may remark, that it appears to us much more beautiful and ingenious than true : for we could eiuHTierate more instances in which the prin- ciple fails than holds good. Gloger's instances also are far from accurate ; for though the kingfisher, for example, hides her shining white eggs in a hole, yet that will not conceal them from the piercing eyes of their chief enemy, the water rat, which, like all burrowing animals, can see with the least possible light. Many birds, also, which lay bright-coloured eggs, make open nests; the thrush, ibr example, whose clear-blue eggs, with a few black blotches, are far from being concealed by the plastering of clay and cow dung upon which they are deposited. The green-finch {Fringilla chloris, Temminck), * See also St. Pierre, Studies of Nature, ii. 393 ; Note. COLOURS OF ECGS. 35 again, which builds an open nest of green moss, lined with horsehair, black or white as it can be had, laj^s clear white eggs with red spots, precisely like those of the common wren and the willow wren (^Sylvia Trochilus), which build covered nests with a small side-entrance ; while the house- sparrow {Fringilla domestica) lays eggs of a dull, dirty green, streaked with dull black, and always builds in holes or under cover. These objections will render it unnecessary for us to follow Darwin into his fanciful account of the origin of the colour of eggs, which he ascribes to the colour of the objects amongst which the mother bird chiefly lives, acting upon the shell through the medium of the nerves of the eye; for, if this were correct, we should have the green- finch and the red-breast, instead of their white eggs, laying blue ones like the hedge-sparrow and the fire-tail. Upon a partial view of the subject, we might bring many facts to support the theory from the colour of the eggs of insects. The nettle butterflies, for ex- ample, the small tortoise shell {Vanessa Urticfe), the peacock (F. lo), and the admirable {F.AtaIa?ita), all lay eggs of a green colour, precisely similar in tint to the plant to which they are attached. On the contrary, the eggs of the miller moth {Apatela Le- porina., Steph.), which are deposited on the grey bark of the willow, are light purple; the beautiful geometric moth {Geometra illmiaria), which Sepp * calls Hercidesje, lays its light pink eggs in the fissm-es of the bark of the elm ; the puss moth {Cerura vinula) lays shining brown eggs on the green leaf of the pop- lar ; and the garden white butterfly {Pontia Brassicce) lays a group of yellow ones on a green cabbage or colewort leaf, but not of so bright a yellow as those of the seven-spot ladybird {CoccuieUa Seplem punctata) . * Sepp, del- Wondercn Gods, Tab, 35, H INSECT TRANSFORMATIONS. patches of which may be found on many sorts of leaves during' the summer months. The immediate origin of colour in the eg'o's of in- sects is ill some cases the inclosed yolk shining through the transparent shell ; but in others, the shell is not uniformly transparent, but ringed, banded, or dotted with opacities of various colours. In the eggs of the driid^er moth {Odoncstis potatoria), for example, there are two circular rings of a green colour, from the green yolk appearing through the shell ; while the rest of the shell is white and opaque, as we have proved by dissection *. Certain ruddy spots on the white eggs of the small rhinoceros beetle (Oryctes 7iasicor}iif}, Illiger) were discovered by Suammerdam to be the red mandibles and spi- racles of the unhatched grub seen through the shell; and the white ground, we infer, was similarly caused by the body of the grubt. This, however, cannot be the origin of the bright red spots on the beautiful yellow egg of the brimstone moth {Rwnia crat^gata, Duponchel), which may, perhaps, have a similar origin to those of birds. With respect to the eggs of birds, it has been re- marked by Mr. KnappJ, that in those "of one hue, the colouring matter resides in the calcareous part ; but where there are markings, these are rather ex- traneous to it than mixed with it The elegant blue that distinguishes the eggs of the fire-tail {Sylvia phoeniciirus, Lath.), and of the hedge-sparrow, tliough corroded away, is not destroyed by muriatic acid. The blue calcareous coating of the thrush's vgg is consumed ; but the dark spots, like the markings on the eggs of the yellow-hammer, house- sparrow, magpie, &c., still preserve their stations on » J. R. f Swammerdam, Book of Nature, i. 13. X JouriKil of a Naturalist, p. 230 SHELLS OF EGGS. 37 the film, thoiin-h loosened and rendered miioilag'inous by this roni^h process. Though this calcareous mat- ter is partly taken up during incubation, the mark- iug's upon these egg's remain little injured even to the last, and are almost as strongly defined ;is when the eggs are first iaiil. These circumstances seem to imply, tliat the colouring matter on the shells of eggs does not contribute to the various hues of the plumage, but, il is reasonable to conclude, are de- signed to answer some particular object not obvious to us; for though the marks are so variable, yet the shadings and spottings of one species never wander so as to become exactly figured like those of another family, but preserve year after year a certain charac- teristic figuring." Most of these remarks will apply to the colours of the eggs of insects : but though we can in most in- stances trace no connexion between the colours of eggs and the perfect insect, there is a striking ex- ception in the egg; of the brimstone-moth mentioned above, which corresponds exactly in colour with the wings of the moth, though the caterpillar is of a dull brown. The eggs of insects, like those of birds, have a shell enclosing the germ of the caterpillar, with a peculiar matter for its nourishment, like the white and yolk of a bird's eQ;g, provitled for the nourish- ment of the contained chick. These several parts, however, are very different in substance from the eggs of birds. The shell of the bird's egg is brittle, opaque, chiefly composed of cha!k (carbonate of lime), and lined with a very thin tough membrane ; while in the egg of an insect the shell is not brittle, is transparent contains no lime ((or it is not per- ceptibly acted upon by diluted sulphuric acid), and no lining membrane can be detected. It appears, indeed, very similar to the transparent portion of a ^8 INSECT TRANSFORMATIONS. goose-quill in the eirn-s of the drinker and other moths which we have dissected*; b\it in the eggs which are deposited in moist places, and in those of spiders, it is extremely thin f- The eg'gs of saw-flies, unts, &c., which grow larger,^ as we shall afterwards show, durinp: the process of hatching', mn^t possess an expansible shell to allow of their enlargement. The yolk and white in the eggs of birds are separated from each other by a very fine membran- ous bag in which each is contained ; but in the eggs of msects, what answers to the yolk consists of distinct minute globules, which float in the white, if we may call it so, for it does not, as we have ascertained, coagulate in boiling water. The eggs of the gypsey-moth {Hypogymna dispor), which we boiled, still continued partly fluid, though the brown matter answering to the yolk was considerably thickened. The portion which does not thicken by boiling most probably forms the first internal fluids of the caterpillar, answering to the blood of quadru- peds. The point where the caterpillar originates, — answering to the scar (Cicatriciila) in the eggs of birds, — we can readily distinguish even by the naked eye in the larger species of eg-gs, as it lies always immediately under the shell*. " Having directed," says the younger Huber, " my close attention to the eggs of ants, I remarked that they were of different sizes, shades, and forms. The smallest were white, opaque, and cylindrical; the largest, transparent, and slightly arched at both ends; while those of a middle size were semi-transparent. On holding them up to the light I observed a sort of white ob- long cloud ', in some, a transparent point might be remarked at the superior extremity; in others, a clear zone above and underneatii the little cloud. The largest presented a single opaque and whitish point *J R. f Kirby and Spence, Intr. S6. GERMS OF EGGS. 39 in their interior. There were some whose whole body was so remarkably clear as to allow of my very distinctly observing- the rings. On fixing- attention more closely upon the latter, I observed the egg open, and the larva appear in its place. Having compared these eggs with those just laid, I con- stantly found the latter of a milky whiteness, com- pletely opaque, and smaller by one half, so that I had no reason to doubt of the eggs of ants receiving a very considerable increase in size; that in elongat- ing they become transparent, but do not at this time disclose the form of the grub, which is always arched*." The germ in the es:g of the garden-spider (Epeira diadema) is described by the accurate Heroldt, as appearing to the eye in form of a minute white point immediately under the shell, and in the centre of the circumference. On examining this point more nar- rowly, it is found to be of a lenticular shape, and composed of innumerable whitish granulations of a globular form, differing only from the globules of the yolk in being smaller and more opaque, as may be seen by squeezing out the contents of a spider's egg into a watch-glass. The most singular circumstance observed by Heroldt was, that in some species of spiders an egg appeared to have a considerable num- ber dispersed upon different points of the surface; but all these ultimately united into a single germf. The eggs of the glow-worm {Lampyris iioctihica)^ as we ascertained from those deposited by one wliich we found in 1829, at Rudesheim, on the Rhine, are golden yellow, somewhat resembling cherry-tree gum, while the internal substance is similar in consistence * M. P. Huber on Ants, p. 68. f Heroldt, Exercit. de Generat. Aranearum in Ovo, and bis Unterg. iiber die Bildung der Wizbellosen Thiere im Eie. d2 40 INSECT TRANSFORMATIONS. to tlie wax of the ears, and in form of i^ronules vvliich are even externally apparent*. We are accustomed to consider the form of eg-gs so nearly regular, that the epithet '' eg'g shaped" is frequently aj)pl;ed to other things, and is well under- stood ; but the eggs of insects, though most com- monly round, are seldom, like those of birds, smaller at one end than at the other, while they often exhibit forms never seen in the eggs of birds, — such as cylindrie, flat, depressed, compressed, prismatic, angular, square, boat-shaped fi &c. These varieties of form are justly referred by Kirby and Spence to the " manifold wisdom" {7ro\v7roiKi\oQ co^na)]: of the Creator ; but we have some hesitation in admit- ting their limitation of this to his " will to vary forms, and so to glorify his wisdom and power in- dependently of other considerations §," and think it would be more truly philosophic to confess our igno- rance where we cannot explain what is above our com- prehension. Paley, indeed, says, such facts " might ijiduce us to believe that variety itself, distinct from every other consideration, was a motive in the mind of the Creator, or with the agents of his will ;" but he immediately adds, "to this great variety in organized life the Deity has given, or perhaps there arises out of it, a corresponding variety of animal appetites, and did all animals covet the same element, retreat, or food, it is evident how much fewer could be sup- plied and accommodated than what at present live conveniently together and find a plentiful subsist- ence ||." The latter remark, we think, completely destroys the former, and it wi'U lead us to what * J. R. t Dumeril, Consider. Generales, p. 49; and Insect Architec- ture, p. 19. X Kphes. iii. 10. ^ Introd., ill. p. 95. II N Plural Theology, p. 345, 14th ed. FORMS OF EGGS. 41 appears to be the true cause of the varied forms of ' the e, with a white transparent stem, more than an inch high, not thicker than a human hair, but much more stiff and rigid. About a dozen of these eggs are deposited in a single and sometimes in a double line, upon the leaves and branches of elder or other trees and plants abounding with aphides, upon which the grubs feed when hatched. The footstalks of these eggs are formed by the mother-fly attaching a drop of gluten to the branch, and drawing it out (as a spider does its line) to the requisite length before the egg is deposited on its summit. As she uses her body for a measure, the footstalks are by consequence all nearly of equal length. It is evi- dently the design of these footstalks to place the eggs out of the reach of the grubs of lady-birds {Coc- cinellce) and of aphidivorous flies {Syrphi), which Twig of lilac, bearing the ep;gs of the lace-wingcd fly (^CUrysopa reticulata, Leach}. The fly is seen resting on the lowest leaf. 46 INSECT TRANSFORMATIONS, frequent the same situations and might devour them. The footstalks are so smooth and slender that these grubs could not climb them, as we have proved by experiment*. The ichneumon-fly {Ophion luteum), whose larvae feed upon the caterpillar of the puss-moth, also deposits eggs with a footstalk ; and what is most singular, these larvae, after they are hatched, during the first stage of their existence, continue attached to the shells of their eggs. It is not till the puss has formed her cocoon that they devour her, and spin their own cocoons under its coverf. The eggs of insects do not seem to hold any regular proportion, so far as regards size, with their parent insects ; for some large moths lay very small eggs, while others of a small size lay eggs consider- ably larger. Kirby and Spence think it probable that eggs which produce females are generally larger than male eggs; with the exception of the hive-bee, in which the reverse takes place. Huber, as we have seen above, found the eggs of ants of different sizes, from which he was led to discover that they increase in size after being deposited. It has been remarked, that animals of prey are less prolific than those which live on vegetable food ; and a similar principle ajjpears to hold to a certain extent amongst insects, the most prolific families belonging, with ie\w exceptions, to those which devour vegetable or animal substances beginning to decay and putrefy. Thus it is that the eagle lays only two eggs, while the wren lays eight, and the pheasant twenty- four; and in the same way the dragon-flies (Lihellu' Una, Mac Leay) do not lay above two dozen eggs, the lace-winged flies (Hcmerobidts) still fewer, and the noontide fly {Mcsembrina meridiana, MiiiGEN) * J. K. t See Insect AiciiUecturc, pp. 195—325, 6. FECUNDITY OF INSECTS AND FISHES. 47 only deposits two egs;s ; while a sinpjle plant-louse (^Aphis)^ as we mentioned before from Rt?aiimur, may be the living progenitor of 5,904,900,000 de- scendants, and the queen of the warrior white ants (Termesbellicosus^S^iEXinm.) produces 31,536,000 eggs in one year. We may illustrate this subject by an extract exem- plifying the proportionate fecundity of the animal king- dom in general. " Compared with the rest of ani- mated nature," says Dalyell, " infusion animalcula are surely the most numerous : next are worms, in- sects, or fishes ; amphibia and serpents, birds, quad- rupeds ; and last is man. The human female produces only one at a time, that after a considerable interval from birth, and but few during her whole existence. Many quadrupeds are subject to similar laws ; some are more fertile, and their fecundity is little, if at all, inferior to that of certain birds, for they will produce ten or twenty at once. Several birds will breed fre- quently in a year, and have more than a single Qg^ at a time. How prodigious is the ditFerence, on de- scending to fishes, amphibia, reptiles, insects, and worms ! Yet among them the numbers cannot be more different. According to naturalists, a scorpion will produce sixty-five young ; a common fly will lay 144 eggs; a leech, 150 ; and a spider, 170, I have seen a hydrachna produce 600 eggs, and a female moth 1 100. A tortoise, it is said, will lay 1000 eggs, and a frog 1100. A gall-insect has laid 5000 eggs; a shrimp, 6000 ; and 10,000 have been found in the ovary, or what is supposed to be that part, of an ascarides. One naturalist found above 12,000 eggs in a lobster, and another above 21,000. An insect very similar to an ant {Mutilla?) has produced 80,000 in a single day ; and Leeuwenhoeck seems to compute four milHons in a crab. Many fishes, and those which in some countries seldom occur 48 INSECT TRANSFORMATIONS. produce incredible numbers of eg-g-s. Above 36,000 have been counted in a herring*; 38,000 in a smelt; 1,000,000 in a sole ; 1,130,000 in a roach ; 3,000,000 in a species of sturgeon; 342,000 in a carp; 383,000 in a tench; 546,000 in a mackerel; 992,000 in a perch ; and 1,337,000 in a flounder. But of all fishes hitherto discovered, the cod seems the most fertile. One naturalist computes that it produces more than 3,686,000 eggs ; another, 9,000,000; and a third, 9,444,000. Here, tiien, are eleven fishes, which probably, in the course of one season, will produce above thirteen millions of eggs; which is a number so astonishing and immense, that, without demonstration, we could never believe it true *." The fecundity of insects is no less remarkable than that of fishes. In some instances, particularly in those already mentioned, the numbers produced from the eggs of a single female, far exceed the progeny of any other class of animals. It is this extraor- dinary fecundity which, under favourable circum- stances, produces countless swarms of insects that give origin to the opinion of their being sponta- neously generated by putrefaction, or brought in some mysterious way by blighting winds. The numerous accidents, however, to which insects are exposed from the deposition of the eg;g till their final transformation, tend to keep their numbers from becoming excessive, or to reduce them when they are at any time more than commonly numerous. * Introd. Observ. to Spallanzatii, xiv. 49 Chapter III. Maternal Care of Insects in depositing: their Eggs.— Solitary Bees.— Wasps. — Ichneumons. — Moths.— Butterflies.— Gnats. — Mistakes of Iii» stinct. Lord Kaimes, in his ' Gentleman F'armer,' men- tions the sino'ular fact that the female sheep, weeks before yeaning-, selects some sheltered spot where she may drop her lamb with the most comfort and security ; and when forcibly prevented from going there, she manifests the utmost uneasiness. But this instance of prospectively providing- for a future progeny is exemplified much more strikingly in most insects, in consequence of the great difference of their economy compared with that of other animals. The sheep and other mammalian quadrupeds suckle their young, and watch over them with the most affectionate care during the earlier and more help- less stage of their existence. This, on the contrary, is only found in a few cases among insects, such as the social bees, wasps, and ants ; for the greater number of species never live to see their descend- ants. The numerous families, indeed, of moths, butterflies, and other winged insects, seldom live more than a few days after they have deposited their eggs, though some other species probably live many months. The latter, however, are only ex- ceptions to the general rule, that insects, after depo- siting their eggs, very soon die. The wisdom of Providence, thcieibre, has endowed female insects with the most wonderful acuteness and skill in anti- cipating the wants of their young, when they escape 60 INSECT TRANSFORMATIONS. from the egs;, and have no mother to direct or pro- vide for them. We have numerous beautiful instances of this in the solitary bees and wasps, whicli perform indefa- tigable labours in hewing out nests in wood and stone, and building* structures of clay, leaves, cotton, and other materials, as we have elsewhere detailed at length*. But we recently met with an example of this, which we shall briefly notice. A small solitary bee, {Chclostoma j^orisoiruie?) not so large as the domestic fly, and more slender in the body, instead of digging into the ground like its congeners t, bores a hole in a tree about the diameter of a wheat- straw, and, when empty, resembling externally the timber holes of the furniture-beetle {Anobium ]jer- tinax), for which, indeed, we at first mistook them, till we were undeceived by seeing the little bees going* in and out. When the work is completed, however, the hole can only be detected by a practised eye, for it is neatly covered with a substance, the nature of which remains to be discovered. It is a grey semi- transparent membrane, somewhat resembling the slime of a snail when dried ; but whether it is secreted by the bee like wax, or gathered from plants like propolis, we cannot tell. As we had a whole colony of these little wood-boring bees in the stump of a growing poplar jit Lee, we cut out several of the perforations, in order to examine the interior. These we found more than an inch deep, and filled to the brim with a thin whitish honey; but, like those of the larger carpenter-bees of a different genus (X3//0- copa), they were divided by several partitions of the same membranous material. The circumstance, however, which induces us to give these details here, relates to the eggs deposited ♦ See Insect Architecture, pp. 24 — G4, &c. t Ibid. p. 43. EGGS OF THE SOLITARY BEE. 51 in these singular perforations. It is obvious, if the eggs were laid in the midst of the liquid honey, that they would either be prevented from hatching, or the grub would be suffocated in the first stai;e of its existeTice. Every chamber of the little nest is so full of honey, that it is difficult to divine how this is to be avoided, and it was only after repeated and anxious researches that we found a solution of the difficulty. It is this : the mother- bee, when she has filled a chamber with honey, glues a single egg, a hair's breadth or two above its sur- face, and at a similar minute distance she stretches the membranous partition, leaving between this and the surface of the honey just sufficient space, and no more, for the newly hatched grub to crawl all round. On opening one of these perforations after the grub had been some time hatched, we found it keeping aloof from the honey, and resting on the upper margin, from which it seemed to have stretched its head, when feeding, to the centre, instead of eating at the circumference. The honey was also then be- come thicker in consistence, and in consequence of what had been consumed, formed a hollow cup*. Remimur describes the nest of a bee of the same family {Andrena cineraria, Fabr.), which is found in the neighbourhood of London, and differs from the preceding in making perforations, not in trees, but in the ground, and lining these with the membranaceous substance that composes the parti- tions and the outer covering. He takes no notice, however, of the prospective ingenuity with which the eg:g is placed above the surface of the fluid honey t. The various species of nests thus prepared by the parent insects for depositing their eggs, are not merely intended for holding provisions and shel * J R. t Reaumur^ Mem., vol. vi. p. 131. f)2 INSECT TRANSFORMATIONS. tering; the youno- grub from the inclemencies of the weather, or from beinjr preyed upon by birds. There are more insiduons and no less destructive enemies than these to guard against. This we shall imme- diately show from the economy of other families of the same order, whose proceedings also strictly illustrate the subject of maternal care. In popular works on natural history the insects alluded to are indiscriminately called Ichnemnons, a name signifying Pryers, and first given by Aristotle to wasps. But recently this term has been considerably restricted, and therefore does not properly apply to many insects whose economy resembles the true ichneu- mons. It is the practice, then, of a very great num- ber of insects, of different orders and families, to take advantage of the labours of other insects in pro- viding for their progeny, in the same way as the common cuckoo and the cow-bunting of America {Emberiza pecoris, Wilson) lay their eggs in the nests of other birds. The venerable Dr. Jenner was the first to publish *, what had long been known to our peasants, that the young cuckoo, when hatched, soon ejects from the nest into which it has been surreptitiously introduced the eggs or young of its foster parent ; but the insects under notice act still more ungratefully. They do not, indeed, live upon the honey or other provision stored up by the builder of the nest for the use of her own young, since, being all carnivorous, this is not to their taste; but they permit the rightful owner of the food to feast and fatten on it, that they may make of him a more substantial repast. The great numbers of dif- ferent species of insects which are reared in this sin- gular maimer would appear almost incredible to one who had not studied their economy ; but it cannot fail to meet the young entomologist at the vei)" * Phil. Trans, for 1788, p. 21 "J. PRECAUTIONS OK INSECTS. 53 outsetof his studies; for it is scarcely possible for many broods of insects to be reared without observing' it. The insidious proceedings of these cuckoo in- sects, as we may not inappropriately call them, give rise to remarkable displays of ing-enuity on the part of the mothers whose progeny is exposed to their felonious designs. It is the usual practice of the solitary bees and wasps to leave the whole task of constructing and provisioning the nest to the fe- male, the male, like an American Indian, taking no part in those domestic concerns. In this case, though she is seldom absent from the spot for more than two or three minutes at a time, some prying Chryds or Tachina often glides into her domicile, and finds time to deposit its egg and to escape before her return. Other solitary bees ex- hibit both more civilization and more culining; for the male assists, al least, in watching and guarding the nest, if he does not lend a hand in its construc- tion. The proceedings of one of these solitary bees {Halictus fulvoci?ictufi, Steph,), indigenous in the vicinity of London, has frequently t'allen under our observation. It constructs a gallery, having on the outside only a single perpendicular passage, but branching out into seven or eight, at the bottom of each of which is placed a globule of pollen kneaded up with hont y about the size of a pea, where an egg- is deposited. Walckenatr, who observed these in- I sects with great care, remarks, that they only work during the night in making their galleries ; and our observations so far agree with his, that though we I have observed some dozens of their nests, we never saw them at work in the day. Instead of this, either the male or the female always remains at the entrance of the nest (which its head exactly fills) ready to give no friendly reception to any enemy that may venture to intrude. We have often seen, a4 INSECT TRANSFORMATIONS. indeed, the ruby-tail fly {Chrysis ignifa), on ap- proaching this vigilant sentinel, fly off in all haste, with evident fear of the consequences. But, as Walckenaer justly remarks, should the partner of its cares return from a foraging excursion, and take two or three circular flights around the entrance to announce its arrival, the sentinel bee immediately makes way by withdrawing into the interior. Should the sentinel bee be absent through any cause i'rom its post, and the forager enter without announcing its arrival, it is immediately driven back and punished for so unpardonable a breach of etiquette*. Another circumstance worthy of notice in the manners of these bees {Halicti) is, that they fly directly into the entrance of their nests without ever alighting upon any contiguous object, a circum- stance which is attributed by Walckenaer to their fear of enemies, numbers of which are always lurk- ing about with evil intent. More than one species of spider and several sorts of wasps lie in wait to make prey of them, besides those we have men- tioned as being on the alert to introduce their eggs into their nest. But their most formidable enemy is a solitary wasp (^Cerceris ornata), numbers of which make their nes's in the very midst of their colonies. The wasps surround the interior margin of their holes with a ramjjart of sand, agglutinated with a whitish mortar, and well polished. The gal- lery is five inches deep, somewhat in the form of an S, in which the female lays her eggs, with a store of provisions for her future young, consisting of the living bodies of her bee neighbours, the ^oov Halicti. It is only on fine days, between eleven and four o'clock, that the mother wasp engages in the chase of the bees, and may be seen flying with the most lively ardour around their nests. When an unfortu- * VValck. Mem. dcs AbciUes Sulit. Paris, 1817. INSECTS OF PREY. 55 nate bee ventures at this time to approach its home, the wasp pounces upon it as a hawk would pounce upon a sparrow, seizes it by the back of the neck, carries it to the ground, and placing; it by the side of a small stone or clod of earth, she turns it round upon its back. Then standing upon its belly in an attitude of conscious triumph, she darts her sting" into the lower part of its head, in such a manner as to stupify j it, but not to kill it outright. As soon as she has in this manner laid in a sufficient store of half-dead bees, she closes up the entrance*. Several species of this family of wasps (^Cerceris mirita, Latr., and C qitadrifasciatay Bosc) are of essential service to agriculturists by provisioning their nests with destructive weevils (^Curculioiiidce) ^ so injurious to orchards and nurseries f- Other famihes of this order in a similar way provide for their progeny a supply of living insects of ditferent species, of which interesting accounts have been given by more than one naturalist |. The insects, however, of these marauding tribes are not permitted to carry on their depredations on their more peaceful neighbours with impunity ; for nature has provided other races of animals to make prey of them. We do not allude merely to birds and reptiles, which devour as many of those carni- vorous wasps as they can catch ; for there is also a numerous tribe of insects who have the address to foil them at their own weapons. All the careful stratagems of the mason-wasp (Odynerus murarius, Latr), in rearing her turretted outworks to defend her premises while she excavates her galleries §, often prove ineffectual in guarding against the insi- * Wa'.ck. ; Latreille, Annates du Museum, torn, xiv.; and Bosc. Ann. Je I'Agric, vol. liii. t Bosc, Ann. de I'Agric, vol. liii. I Sec Insect Architecture, pp. 26—33. § Ibid., pp. 30—32. 56 INSECT TRANSFORMATIONS. dious intrusion of a common ichneumon-fly (Pimpla manifestator, G raven horst), easily known by its be- ing black, with the legs red. This ichneumon some- times pays a visit to the nest of the wasp before it is completed, for Reaumur has seen one peep into the entrance and then start back as if afraid of its depth ; but, for the most part, she waits patiently till the wasp, having laid in a store of caterpillars for the yomig one, closes up the doorway with a bar- ricado of kneaded clay. It is this very barricado which the ichneumon determines to assail in order to find a nest ready prepared and stocked with provi- sions for her own progeny. With this design she makes use of her ovipositor, which is as admirably adapted to the purpose as those of the saw flies or the tree-hoppers {CicadcB). The ovipositor of all the true ichneumons {Ich- nemnonidce) is similarly constructed, consisting of a borer enclosed in a sheath, which opens through its whole length like the legs of a pair of compasses. It is longer or shorter, and stronger or more slender, according to the substances which it may be neces- sary to penetrate when the eggs are deposited. The description, therefore, of the ovipositor of the one just alluded to (P. incniifesiator) will be sufficient to give the reader a distinct notion of the others. l?eing intended to penetrate into the deep holes dug by mason-wasps, the ovipositor of this insect is nearly three inches long, and, as it is not concealed in the body like those of gall-flies, it appears like a tail formed of a long black bristle. On examining this a little more narrowly, we find that what appears to be a single bristle is in reality three, two side ones forming a sheath, and the middle one a borer or brad-awl for piercing the clay barricado of the mason-wasp's nest. The termination of the borer is not, however, smooth, like that of a brad- ICHNEUMONS, 57 awl, but toothed like a saw, only the teeth, seven or eight, are not oblique, but perpendicuhir, a structure better fitted for acting upon clay, as the teeth will not become so readily clog-g-ed, and the instrument will be more easily retracted. The figures will make this more perspicuous than the best description. a, the Pxmpla mmrfestntor ; b, its ovipo>itor opened outwaivU; c c c c, magiiilied view of its ovipositor ; d, the tootiied point of the borer. In order to study the economy of the mvaon- wasps {(Jdyncri) more effectually, Reaumur made an artificial vespiary of sand and mortar upon a wall, which at the same time gave him 'j^n excellent opportunity of observing the manoeuvres of the ich- neumons. '' I perceived," he tells us, " one of these ichneumons, at the instant it alighted on the spot under which so many of the little green caterj)illars had been stored up by the wasps. Its long tail, which it carried horizontally, appeared to form but 0!ie bristle, though it was really composed of three ; and though it carried it on a line with its body, it soon showed me that it was capable both of raising and lowering it, as well as of bending it in various directions, and in different proporiions to its length. It moved its ovipositor so as to bring it into a bent position under its body, protruding it even beyond its own head ; taking care to direct it into the barri- 58 INSECT TRANSFORMATIONS. cadoed nest of the mason-wasp. But although the insect appeared not to he disturbed by my obser- vations, yet I was unable to perceive whether the toothed portion of the borer was pushed beyond the sides of the sheath. What I did see, however, con- vinced me that the instrument was worked in a manner well adapted to make its way through the mortar ; for she turned it half round alternately from right to left and from left to right, as a carpenter would his brad-awl, and employed altogether more than a quarter of an hour before she succeeded in penetrating to a sufficient depth*." Ichneumon-flies ovipositing, a a, an ichneumon fly. h h, its ovipositor, c, an ichneumon, which has just bored through the closed substance of a sand-wasp's nest at e, into which her ovi- positor, d, descends to the coil of caterpillars at /, where the egg is laid. * Reaumur, Mem. vi, p. 3l)4. PARASITE-EGGS. 59 Another parasite (Pimpla strobilellfB, Fabr.) is F armed witli a long ovipositor, with which it deposits its etrgs in larvae that burrow in the fruit-cones of the fir. The intrusion of these parasite-eggs into the nests of insects is often an exceedingly puzzling circum- stance to naturalists, in their earlier researches ; and sometimes even deceives those of considerable expe- rience and acuteness into the supposition that the insects ultimately produced are in reality those of the original builder of the nest. These deceptions frequently occur in the numerous species of vege- table galls, originating chiefly in the economy of a beautiful family of insects {ChalcidideBy Westwood). When the gall-fly {Cynips^ has deposited its eggs on the bud or the leaf of a plant in such a manner as to ensure their being surrounded with a thick coating of vegetable substance, they are not on that account se- cure from the insects just alluded to; for the Chalets, armed by nature with an instrument for the purpose, ! can penetrate in any direction the largest oak-apple i or bedeguar of the rose*. The most obvious dis- tinction between these parasites and the true gall-flies, is, that in the latter the ovipositor is partly concealed, while in the former it is altogether external, like the ichneumons in the preceding figure ; but this dis- tinction is of course wanting in the male insects. It was the observation of different species of insects, produced in this manner from the same sort of gall, which betrayed the illustrious Redi into the fancii'ul notion of their being generated by a vegetative and sensitive soul in the plant itself, to which also he attributed the generation of the grubs found in nuts, cherries, and other fruits. '' There is nothing," as Reaumur justly remarks, *' more fitted to humi- liate the best reasoners, and to inspire them with a * See Insect Architecture, pp. 375 — 384. I 60 INSECT TRANSFORMATIONS. well-founded distrust of novel opinions, than to see a man like Redi, who had declared open war a2;ainst popular prejudices, and successfully com- bated many of them, thus adopting- a notion so improbable, or (to use a stronger term) so pitiable*." It was Redi's countryman, Malpighi, who first dis- covered the genuine history of gall-flies; but when we consider that from the bedeguar-gall of the rose alone no less than three different species of insects may proceed, two of which {Callimone bedcguarU, and Eurytoma stigma, Stephens) are parasites, Redi had some cause foi being puzzled to explain the ])henomena. Two other distinguished naturalists, Goedart and Ray, found no less difficulty in accounting for the progeny of ichneumons issuing from the caterpillars and chrysalides of butterflies. Ray, indeed, lived to ascertain the fact ; but he was at one time inclined to believe, with Goedart, that when, fiom any defect or weakness. Nature could not bring a caterpillar to a butterfly, in order that her aim might not be en- tirely defeated, she stoj)ped short, and formed them into insects of a smaller size, and less perfect struc- ture f. M. Goedart even persuaded himself, says Reaumur sarcastically, that he had observed the caterpillar interesting itself for its infant progeny, by weaving for them an envelope of silk. It was also fancied that what was wanting in size in the parasite- flies, when compared witii tlie expected biitterfiy, was made up in their greater numbers | ; with as much probability, says Reaumur, as that a cat would kitten a number of mice. The simple facts which we shall now state, will point out the origin of these strange mistakes. * Reaumur, Mem. iii. p. 4/6. f Ray, tiist. Ins., I'ref. xv., and Cant. 137. I Goedaitj quoted by Reaumur, vol. ii. p. 415. PARASITE-INSECTS. 61 It must have occurred to the least attentive observers of the very couiinon cabbage-caterpillar {Pontia BrassicfB)^ that when it ceases to feed, and leaves its native cabbage to creep up walls and palings, it is often transformed into a group of little balls of silk, of a fine texture and a beautiful canary yellow colour; from each of which there issues, in process of time, a small four-winged fly (Micro- gaster gloineratus, Spinola), of a black colour, ex- cept the legs, which are yellow. By breeding these flies in a state of confinement, and introducing them to some cabbage-caterpillars, their proceedings in de- positing tlieir eggs may be observed. We have more than once seen one of these little flies select a cater- pillar, and perch upon its back, holding her ovipositor ready brandished to plunge between the rings which she seems to prefer. When she has thus begun laying her eggs, she does not readily take alarm ; but, as Reaumur justly remarks, will permit an ob- server to approach her with a magnifying glass of a very short locus. Having deposited one egg, she withdraws her ovipositor, and again plunges it with another egg into a different part of the body of the caterpillar, till she has laid in all about thirty eggs. It is not a little remarkable, that the poor caterpillar, whose body is thus pierced with so many wounds, seems to bear it very patiently, and does not turn upon the fly, as he would be certain to do upon anotiier caterpillar should it venture to pinch him; a circumstance by no means unusual. Sometimes, indeed, he gives a slight jerk, but the fly does not appear to be at all incommoded by the intimation that her presence is disagreeable. The eggs, it may be remarked, are thrust suffi- ciently deep to prevent their being thrown off when the cateipillar casts its skin ; and, being in due time hatched, the grubs feed in concert on the living body of the caterpillar. The most wonderful circuUi- £ 62 iNSECT TRANSFORMATIONS. stance, indeed, of the whole phenomenon, is the instinct with which the grubs are evidently g:uided to avoid devouring; any vital part, so that they may not kill the caterpillar, as in that case it would be useless to them for food. When full c^rown, they even eat their way through the skin of the cater- pillar without killing it ; though it generally dies in a few days, without moving far from the place where the grubs have spun their group of silken cocoons in which to pass the winter. Generation of Ichneumons, a a, the cateriiillarof Pontin Bran- siccv. b. the efifgs of that buttertly glued to a leaf, c, Mieroijastev glomrrntus, inapnifiei]. d d d, a. niagniticd view of a disstcted caterpillar, in whose body a number of ichneumon cater[)illars have been hatched, e, silk cocoons spun by tlie ichneumons. /. prubs spinning cocoons, g, grubs eating their way out of the caterpillar. PARASITE-INSECTS. 63 But it is not only in the nests of bees and wasps, or in the bodies of caterpillars, that these provident mothers contrive to deposit their eggs ; for many of them are so very minute, as to find in the egg-s them- selves of larger insects a sufficient magazine of ibod for their progeny ; and accordingly, piercing the shell with their ovipositor, they thrust their own into the perforation. The most common instance of this which we have remarked occurs in the eggs of spiders ; patches of which may be found almost everywhere under the cross bars of palings, and the copings and corners of walls. Though spiders, for the most part, not only cover their eggs with a thick envelope of silk, but also remain near to protect them from enemies, yet a small four-winged fly (Cryptus, Fabr.), and, if we are not mistaken, two-winged flies {Muscid(Ey Leach), also, outbrave the danger of being caught and immolated by the mother spider, and introduce their eggs either into or among those of their powerful enemy. These spider's eggs are subsequently feasted upon by the progery of the flies, — a very natural reprisal for the ravages com- mitted by this carnivorous race upon the whole gene- j ration of their fellows. That the mother flies actually ■I pierce the eggs of other insects was observed before I! the year 1730, by the accurate Vallisnieri, who says, I '* I have seen with my own eyes a certain kind of \ wild flies deposit their eggs upon other eggs, and [l bore and pierce others with an ovipositor {acnUusi)^ !j by means of which they have introduced the egg*." j Count Zinanni, another Italian naturalist, told Reau- j mur, that, his attention being attracted by a small fi ichneumon fluttering about the eggs of butterflies, 1.} he soon observed it alight and fix upon one of these |i eggs; and, without being incommoded by his ol)- \[ serving her proceedings through a strong magnitier, ; * Vallisnieri, I.elteie, 80. 64 INSECT TRANSFORMATIONS. she bent her ovipositor, and plunged it into the effg. She performed the same operation upon many other eggs, which he carefully put under cover; and in about tliree weeks had from them a brood of flies of the same species with the one whose remarkable j)roceedii!gs he had watchetl*. A writer in the Magazine of Natural History (Jan. 1830) gives an account of a numerous brood of a very minute species of ichneumon, supposed to be an egg parasite {Platyga.'iter oviilorvm? Stephens), which was produced from the caterpillars of the larae white cabbage-butterfly (Poniia Brassicce). Having enclosed a number of these in a wire cage, five or six of them soon left off feeding, and crawled about the cage. " June 30," he ])roceeds, " I found them resting on large clusters of minute cocoons of an ovate form, tlie largest not exceeding two lines in length, and about the thickness of a caraway-seed. Each was enveloped with a fine yellow silk, re- sembling that of the common silkworm {Bombyx Mori). On these clusters the caterpillars remained the whole day without moving. Fresh leaves were given to the rest ; but in the course of the day they all left off feeding, crawled about the cage, but underwent no other change. Early next day, I found they had, with the exception of two or three, all ejected the parasitical progeny they had been impregnated with ; and, like the preceding caterpillars, continued resting on the clusters they liad formed : the remaining three followed the ex- ample of the others ; and the last operation of these devoted caterpillars was to envelope each cluster in a veil formed of the most delicate web f." Jt is not a little interesting to remark, that this circum- stance corroborates the statement before given from • lluaumur, Mem. vol. vi, p. 297. f Loutlon's Mag. Nat. Hist. iii. 51. PARASITE-INSECTS. 65 Goedart, and disbelieved by Reaumur and subse- quent naturalists : but we think it so very extra- ordinary, that we are much inclined to think the observer (T. H. of Clapham) has unwittingly fallen into mistake. " Some of them," he continues, " ex- ecuted the task ; but the greater part were too feeble to complete it; and in the course of three days more they became motionless, and gradually, one after another, fell shrivelled and exhausted to the bottom of the cage." Some of the clusters contained up- wards of a hundred cocoons, and others not more than sixty. By July 12, the perfect flies made their appearance by opening a sort of lid at the end of each cocoon. The flies seem to differ little, except in size, from the common ichneumon of the same caterpillar {Microgaster glomeratus) ; but, supposing them to be in the first instance e^g parasites, they must have been deposited among, not in the eggs of the butterfly. The minuteness of some of these parasite-insects may be partly conceived from the fact mentioned by Bonnet, — that the egg of a butterfly, not bigger than a pin's head, is sufficient to nourish several of them ; for out of twenty such eggs of butterflies, a pro- digious number {une quantite prodigieuse) were evolved *. Few species of the plant-lice {Aphides) are a great deal larger than the butterfly's eggs de- scribed by Bonnet ; yet these also have a parasitical enemy (Microgaster Aphidum, Spinola), which plunges its eggs in their bodies; but the larva?, when hatched, are by no means safe, being liable to the attacks of another fly of the same family (Gelis agilis, Thunberg), as Dr. Turton informs us f. * Bonnet, GEuvres, 8vo. ii. 344. Kirby, referring to this pas- sage, assigns, by mistake, only two to each egg. Introd. i. 342. f Transl. of Linn. iii. 48. e3 GB INSIiCT TRANSFORMATIONS. It is not comnioii, however, for the ichiieuinon- flies to deposit their eggs, in the bodies of perfect insects, as in most cases they prefer the egg-s, larvie, or pupae ; but instances are on record of their grubs having been found in the former. The troublesome cock-roach {Blattd) is selected by a parasite-fly (Evania apendigaster, Fabu.), as remarkable in form as it is rare in occurrence, in Britain at least. It has been found in the vicinity of London ; but, were it abundant, it might tend to reduce the num- bers of these black beetles, as they are incorrectly termed, the pests of the kitchen. Magnified view of a parasite-fly (^Evania apendigaster). An insect parasite, still more singular in form, and of still rarer occurrence, was discovered by Kirby, above thirty years ago, on the black bronze bee {Andrena nigro^nea, Stephens). " I had pre- viously,'' he remarks, " more than once observed upon other species something that I took to be a kind of Acarus, which appeared to be immoveably fixed just at the inosculations of the dorsal segments of the abdomen. At length, finding three or four upon a specimen of this bee, I determined not to lose the opportunity of taking one off to examine and de- scribe; but what was my astonishment, when, upon my attempting to disengage it with a pin, I drew forth from the body of the bee a white fleshy larva, PARASITE-INSECTS. 67 a quarter of an inch in length, the head of which I iiad mistaken for an acariis ! {bee-louse). After I had examined one specimen, I attempted to extract a second ; and the reader may imagine how greatly my astonishment was increased, when, after 1 had drawn it out but a little way, £ saw its skin burst, and a head as black as ink, with large staring eyes and antennae, consisting of two branches, break forth, and move itself briskly from side to side. It looked like a little imp of darkness just emerged from the infernal regions. My eagerness to set free from its confinement this extraordinary anitnal may be easily conjectured. Indeed i was impatient to become better acquainted with so singular a creature. When it was completely disengaged, and I had secured it from making its escape, I set myself to examine it as accurately as possible ; and I found, after a careful inquiry, that I had got a nondescript, whose very class seem.ed dubious*." Of the manner in which this singular insect {Stylojjs) introduced its eggs into the body of a bee nothing is yet knoA'n, and its rarity i)uts it out of the reach of the most eager observers. Several species of the same genus have since been found near London, and an allied genus {Xenos) has since been discovered parasite in wasps by Professor Peck, in America. Bee- Parasite. (^Stylops MelittcB, Kiubv.) De Geer was one day much surprised to ob- serve a small white grub sucking the body of a young spider {Epeira diadcmd), having attached itself * Monogr. Ap. Angl. ii. 113. 68 INSECT THANSFORMATIONS. firmly to the abdomen. Having- pnt it into a glass, he remarked a few days afterwards, that the spider had spun the outline of a vertical web, had stretched threads from the top to the bottom, and from one side to the other of the glass, together with the rays of a net, but without the circuhir threads. The most singular circumstance was, that the parasite grub was suspended in the centre of this web, where it spun its cocoon, while the exhausted spider had fallen dead to the bottom of the glass*. These examples will suffice to prove the anxious care of the mother insects in depositing their eggs where tlieir progeny may find abundance of food. The tact with which they discover this is one of those mysteries of nature which are apparently beyond the penetration of man ever to discover; for it is seldom that the mother insect herself feeds upon the same, or similar substances, as her larvte, and yet she is well aware of what is appropriate for them. The ichneumon-flies, whose history we have just been sketching, eat little, except, perhaps, a small quantity of honey from the nectary of a flower, and yet they know that their progeny must be fed by living insects ; the butterflies and moths, whose scanty repast also consists solely of the honey of flowers, never make a provision of this for their caterpillars, but deposit tlieir eggs on plants and trees where their young may eat abundantly of leaves or other parts " after their kind." In making these selections, each species exhibits some pecu- liarity well worthy of observation. Some confine themselves to one particular sort of plant, and never select any other; some make choice indilferently of two or three sorts; while others take a wider range, and fix upon plants of very ditferent qualities. To exemplify this, we might mention some thousands of * De Geer, Memoires, vol. ii. p. 863. LOCALITIES OF VARIOUS SPECIES. 69 instances, but it will be sufficient to say, that we never find the eggs of the small tortoise-shell but- terfly {Vanessa urticce) on any plant but the nettle ; its congener, the painted lady (Cynthia cardui, Stephens), though it prefers the spear- thistle, is sometimes found on the nettle, as is the comma {Vanessa C. Album), though it seems to prefer the hop ; while we have found the eggs of the lackey- moth {Clisiocampa neustria) on almost every bush and tree, from the sweetbriar to the oak, in woods, hedges, orchards, and gardens, without any apparent preference beyond the accident of the mother moth alighting on a particular branch. In the same way almost all those which deposit their eggs on salad plants, such as the great tiger {Arctia Caja, Ste- phens), will as readily select the nettle as the lettuce or dandelion*. It is worthy of remark that our native insects frequently make choice of exotic plants, by means of the instinctive tact which enables them to discover such as suit their purpose. The death's-head hawk moth {Acherontia Atropos), for example, is now usually found on the potatoe and the jasmine, but previous to the introduction of these into Britain, it probably confined itself to the bitter sweet {Sola nnm dulcamara). W^ have known the moth taken in Ayrshire, where this plant is abundant. An instance in point has just occurred to us in one of the minute leaf-miners. Upon the leaf of an exotic plant {Cineraria cruenta') kept in a garden- pot in our study, we were not a little surprised to observe the tortuous windings of a miner, considerably different in the outline from any we had before examined. Though it was so late as December, also, the grub seemed very active, and would sometimes mine nearly half an inch of the leaf in the course of the day. It 70 [NSECT TRANSFORMATIONS. was transformed within the leaf, in a few days, into a pupa, and being put under a belt-glass, a small two- winged fly (Tephritis SerratulcB?) made its appear- ance in about a fortnight. In some garden-pots, in another room of the same house, were exotic plants of the American groundsel (^Senecio elegans), the leaves of which were crowded with miners, whose paths, however, were so very different as to indicate a different species ; but upon their transformation into perfect insects, they turned out exactly the same. They proved, indeed, to be the same with the leaf- miners of the swine-thistle {Sonchus oleraceus). Leaf-mining maggots, a, the fly {Tephritis Scrratulrv ?). b, mined leaf of sow-thistle (^Sonchus oleraceus'). i\ mined leaf of Senecio elegans. d d. mined leaf of Cineraria cruanta. LOCALITIES OF VARIOUS SPECIES. 71 immerous specimens of which we collected in the immediate vicinity ; but the flies of these, from their previous exposure to the cold out of doors, did not appear till a month later. It is worthy of remark, that the two exotic plants are of the same natural family {Co7npositce) ; yet, notwithstanding the simi- larity of the common groundsel (Saiecio vulgaris) to the American, not one leaf of the former was found mined, thoug-h it is an abundant native plant*. It is no less remarkable, that the mother insects of the larvae which live solitary and those which live in society take care to deposit their eggs with regard to the respective destinations of their progeny. In our earlier studies we remember being much inte- rested with Harris's description of the admirable butterfly {Vanessa Atalanta)^ flitting rapidly and stealthily from field to field, and depositing only a single egg on a single nettle in each, as if she were afraid of overstocking one place and leaving others uninhabited by her descendants f. Our subsequent observation of the manners of the insect itself has led us to doubt the accuracy of Harris; for we think it will hold as a pretty general principle, that the mothers of solitary caterpillars, for the most part, deposit several eggs on the same plant, often at no great distance, and sometimes on the same leaf. No class of caterpillars could well be considered more solitary than those of the hawk-moths {Sphingid(B^ Leach), yet we have found from two to three eggs of that of the poplar- hawk (Smerinthus Populi) upon the same leaf, and a similar number of the eggs of the puss-moth, the larva of which is also solitary, on one leaf + ; while of the admirable butterfly above alluded to, we found, in 1825, as many as from three to six on every plant in a small patch of about a dozen * J. R. t See Harris's Aurelian, vi. fol. Lond. 1778. + See Insect Architecture, p. 192. 72 INSECT TRANSFORMATIONS. nettles, in Copenhagen-fields, Islington. A similan' deposition of eggs is made by several of the mothers of the subsolitary caterpillars which live in the wood of trees. Of this we had a good example in the clear under-vving {JEgtria asiliformis), above a score of the small black eggs of which we tbund deposited in a scattered manner on the trunk of a single poplar at Lee *. The most singular disposal of eggs with which we are acquainted in the economy of insects is exem- plified in the common gnat {Cule.v pipiena, Linn.). It is admirably described by Reaumur, though it seems first to have been discovered by Langallo, who mentions it in a letter addressed to Redi, printed at Florence in 1679 ; and by Alloa, who actually saw the eggs laid, and afterwards sketched a figure of them. Those who wish to witness this singular opera- tion must repair before five or six o'clock in th€ morning to a pond or a bucket of stagnant water frequented by gnats ; when Reaumur went later in the day he was always disappointed. The facts of this disposal of her eggs by the com- i mon gnat are sufficiently curious to excite attention to them ; and, therefore, it is not easily to be under-! stood how the following erroneous and fanciful account originated. *'The manner," says Goldsmith, " in which the insect lays its eggs is particularly curious ; after having laid the proper number on the surface of the water, it surrounds- them with a kind of unctuous matter, which prevents them from sink- ing, but at the same time fastens them with a thread to the bottom^ to prevent their floating away, at the mercy of every breeze, from a place the warmth of which is proper for their production, to any othei where the water may be too cold, or the animals, its''^' cuemies, too numerous. Thus the insects, in theiif * J. R. RAFT OF EGGS OF THE GNAT. 73 ogg state, resemble a buoy wliich is fixed by an anchor. As they come to maturity, they sink deeper, and at last, when they leave the egg- as worms, creep to the bottoiri^y This fable, which was first men- tioned by Pliny, is repeated verbatim by Bing-leyf The impossibility of a g-nat spinning a thread, and plunfring into the water to fix it at the bottom, never struck these writers. We are the more anxious to expose these erroneous accounts, from a persuasion that a tas'te for natural history has been more injured by numerous similar statements, which could not be verified by a student, in many popular works, than by the driest skeleton descriptions of those who have merely pursued Natural History as a science of names. The problem of the gnat is to construct a boat- shaped raft, which will float, of eggs heavy enough to sink in water if dropped into it one by one. The eggs are nearly of the pyramidal tbrm of a pocket gunpowder-flask, rather pointed at the upper and broad at the under end, with a projection like the mouth of a bottle. The first operation of the mother gnat is to fix herself by the four fore legs to the side of a bucket, or upon a floating leaf, with her body level with and resting upon the surface of the water, excepting the last ring of the tail, which is a little raised ; she then crosses her two hind legs in form of an X, the inner opening of which is intended to form the scaffolding of her structure. She accordingly brings the inner angle of her crossed legs close to the raised part of her body and places in it an egg, covered, as is usual among insects, with a glutinous fluid. On etich side of this egg she places another, all which adhere firmly together by means of their glue, and jform a triangular figure thus **, which is the stern * Goldbinilh, Animated Nature, vi. 337. I Bingley, Animal Biography, iii. 439, 3d ed. F 74 INSECT TRANSFORMATIONS. of the raft. She proreeds in the same manner to add eg^ after egg in a vertical (not a horizontal) position, carefully regulating- the shape by her crossed logs; and as her raft increases in magnitude, she pushes the whole gradually to a greater distance, and when she has about half-finished she uncrosses her legs and places them parallel, the angle being no longer neces- sary for shaping the boat. Each raft consists of from two hundred and fifty to three hundred and fifty eggs, which, when all laid, float on the water secure from sinking, and are finally abandoned by the mother. They are hatched in a few days, the grubs issuing from the lower end; but the boat, now composed of the empty shells, continues to float till it is destroyed by the weather *. Gnats forming their egg boats, a, represents the commencement of the boat of eggs; b, the boat about two-thirds completed; c, the perfect boat resting ou the surface of the water. Kirby justly describes this little vessel as resembling a London wherry, being sharp and higher, as sailors f>ay, fore, and aft, convex below and concave above, and always floating on its keel. " The most violent agita- tion of the water," he adds, " cannot sink it, and what is more extraordinary, and a property still a desideratum in our life-boats, though hollow, it never becomes Reaumur, Me 111. IV. p, G21. RAFT OF EGGS OF THE GNAT. 75 filled with water, even though exposed. To put this to the test, 1 placed half a dozen of these boats upon the surface of a tumbler half-full of water : I then poured upon them a stream of that element from the mouth of a quart bottle held a foot above them. Yet after this treatment, which was so rough as actually to project one out of the glass, I found them floating as before upon their bottoms, and not a drop of water within their cavity *." We have repeatedly pushed them to the bottom of a glass of water, but they always came up Immediately to the surface appa- rently un wetted. Magnified view of the boat of gnats' eggs. "We have contented ourselves with giving here only a few examples of the maternal care which is displayed by insects in depositing their eggs, though we could have filled the volume with similar details. The instincts which are thus displayed are of the most interesting description ; and they cannot fail to impress the most careless observer with a deep reve- : rence of that providential wisdom by which they are implanted in these small and feeble creatures for the maintenance of their race. But it is not essential, in order to produce this reverence, to exaggerate the cir- cumstances under which these remarkable peculiarities are displayed. The infallibility of the instinct of in sects in such cases is, in most books of natural his- tory, maintained to be without exception. " Led by an instinct," say Kirby and Spence, " far more un- • Introd. iii, p. 32 f2 76 INSECT TRANSFORMATIONS. erring" than the practised eye of the botanist, she re- cognizes the plant the moment she approaches it*." And again, they talk of " the vnerring foresight with which the female deposits her eggs in the precise place where the larvae when excluded are sure to find suitable food t-" This unconditional position requires, however, to be considerably modified to make it cor- respond with the facts. The experiment we gave from lledi in our first chapter, in which the carnivorous flies laid their eggs on the silk and paper covering tainted meat, will occur to every reader as one striking- exception ; and we can mention several others still more marked. When Dr. Arnold discovered that most singular parasitic plant, thekrubut, of Sumatra, (Rqfflesia Aruoldii^ Brown,) which consists of a flower only, without leaf or stem, and of the extra- ordinary diameter of three feet, he perceived a swarm of flies hovering over the nectary, and apparently laying their q£!i<^^ in its substance, mistaking it most probably for carrion, as it smelt like tainted beef|. A similar mistake is committed in our own country, when the common blow-fly {Miisca vomiloria) lays its eggs in the foetid funguses {Phalli, Agarici^ &c.) apparently under the notion that these are genuine carrion §. This may be more particularly observed I on the singular class of plants, stapdias, which are I so common in our hot-houses: whole families of maggots are constantly born to starve in their foetid Ij flowers. These are instances of the mistakes of instinct in i circumstances where it depends upon the information of the senses ; and similar mistakes frequently occur where the higher powers of human rationality are deceived by analogous phenomena. The fine nutty flavour of cherry laurel water and of prussic acid * Iiitrod. i. p. 340. t Ibid. iii. p. 65 ; R.Brown, Linn. Trans, vol.xiii. ^ Smellie, Thilos.of Nal. Hist. MISTAKES OF INSECTS. 77 i would be certain to deceive the inexperienced ; and Majendie's servant actually fell an immediate vic- tim to her desire of tasting the prussic acid which she found in his laboratory. This would be consi- dered perhaps a mistake arising from the artificial habits acquired in society, by those who maintain that animals, guided by instinct, never mistake poison for food. But w^e may add another curious instance or two of similar mistakes in the inferior races. The common earth-worm (Lumhricus ttrrestris) is instinctively afraid of moles ; and no sooner does it hear any subterranean noise, or feel any shaking of the ground, similar to those indicative of the ap- proaching movements of its enemy, than it makes a speedy escape to the surface. Every boy knows how to take advantage of this to procure fish-baits, by thrusting a spade or a stake into the ground, and moving it backwards and forwards, to imitate the advance of a mole burrowing in search of prey. 1 The worm, unable from its instinct to discriminate ! between its subterranean enemy and the spade, darts I into day-light, and is instantly captured for the boy's i bait-bag. The lapwing {Vaiiellus cristafus, Meyer), it is stated by Dr. Anderson in his ' Bee,' is aware of this instinctive fear in the earth-worm of sub- terranean concussions or noises ; and when it can- not find sufficiency of slugs*, &c. above ground, it pats with its feet, till the earth-worms, mistaking it for an advancing mole, come forth to be feasted upon. It is well known that, whenever a hawk appears, he is immediately surrounded by a host of small birds, particularly swallows, which dart at him and tease him, fop the purpose, as may be supposed, of distracting his attention, on the principle that *" Nourriture ; — insectes, aralgii6e.s, vers, el petits lima^ons." Temm'.nck:, Manuel d'Ornilhologie, p. 552, 2d edit 78 liNSECT TRANSFORMATIONS. * wealth makes wit waver.' Be this as it may the cuckoo, which bears a strong resemblance to a • hawk when on the wing, is certain to be accom- panied by a similar retinue of small birds wherever it flies. In the north this is so commonly observed, that the cuckoo is popularly believed to be always attended by a titling or pippet (Anthus pratcnsisj Bechstein), which it is further imagined, has been its stepmother and nurse from tiie ^g^: this, indeed, is the bird whose nest the cuckoo most frequently selects to deposit the eggs, which she so strangely and unnaturally abandons ; though it is more pro- bable that it is not on this account, but because she ; appears to be a hawk, that the pippet and other small I birds persecute her. Linnaeus records in his ' Lachesis Lapponica,* ' that at Tornea there is a meadow, or bog, full of} water-hemlock (Cicuta virosd)^ which annually f destroys from fifty to a hundred head of cattle. It seems that they eat most of it in spring, when first turned into the pasture, partly from their eagerness lor fresh pasture, and partly from their long fasting and greediness, the herbage being then short. Be- sides, from the immersion of the hemlock under water, it may not have the proper scent to deter them. A similar destruction of cattle from the same cause occurs in the wide meadows of Leinings *, * J. R., in Mag. of Nat. Hist., i. 374. 79 Chapter IV. Hy'ieriiatiouof Inse(;t Eggs. — Ingenuity of Moths. — Singularities of Co- chenille Insects and of Spiders. — Kxperiments of Spallanzani and John Hunter. The assertion of Paley that " the human animal is the only one which can clothe itself*," though it accords with what is known of quadrupeds, birds, and fishes, by no means holds good in the insect world, in which it may be disproved by the most superficial observer t. Men, indeed, proceed by means of rea- soning and experiment to the discovery of such ma- terials as are best fitted for protecting their bodies against the vicissitudes of temperature, and other changes of weather; while insects are taught by the Governor of the Universe to select instinctively the best materials for their clothing. This is exemplified in a very remarkable manner in the coverings made by different families for protecting their eggs> as we shall now describe. The maternal affection of the eider duck (^Aria's mollissima, Linn.) has frequently been celebrated by naturalists, from her stripping the down from her own breast to form her nest, a circumstance which is also exemplified in the. common rabbit; but both of these animals are outrivalled by more than one moth : — for the latter, not contented with a nest made of their own down, take pains to cover with it each individual ^gg. The provision which nature has" made for this purpose is worthy of attention. The female, for ex- ample, of the gypsey-moth (Hypogymna dispar) has the hinder parts of Iter body thickly clothed witli a * Natural Theology, p. 230, 11th edit. f See ' Insect Architecture,' chaps, x., xii., &c. 80 INSECT TRANSFORMATIONS. soft down of a hair-brown colour, which is wanting in the male, evidently because to him it would be of no use. As a covering for her own body, it can be of but small service, since she emerges from her pupa-case during the hot days of August, and does not usually live more than a week or a fortnight. Its chief or sole purpose, therefore, is to furnish a co- vering for her eggs. When about to lay, the mother gypsey-moth places herself on the trunk of an oak or an elm, invariably with her head downwards, the reason of which posi- tion will be immediately explained. Without the aid of her legs, which are too short to be used like those of the gnat by way of rule and compass, she contrives to place her eggs in the form of an inverted cone. She first makes a little bed of this down, into which she thrusts the egg intended for the point of her cone ; and this egg, being covered with adhesive gluten, attaches around it all the hairs of the down with which it comes in contact, and also sticks to the bark of the tree, from its being pushed home. Pro- ceeding in the same manner, she continues for seve- ral hours adding to the mass ; but she does not in general finish the operation in less than two days, indulging in occasional rests when fatigued with her labour. At intervals, also, she takes care to protect the eggs placed in the cone with an exterior covering of the same down There is one part of these opera- tions not a little remarkable. In the bed which she first makes for the eggs, the hairs of the down either point at right angles to the bark of the tree, or at least are tossed down with little regularity ; but in the external coping, which is designed to keep out the winter rains, the hairs are carefully placed in a sloping direction, like the tiles on a house, or the pile of a well brushed hat, pointing downwards towards the base of the cone The latter is usually concave, be- INGENUITY OF MOTHS. 81 cause, when the moth takes her occasional rests, she never moves from the spot, but remains with her tail thrust in amongst the eggs. We have given these details from observations made in the Pare at Brus- sels, in August, 1829*; and our entomological readers will perceive, that though they do not disagree with the facts observed by the accurate Rtjaumur, we have added several particulars not mentioned by him f. In order to preserve some specimens of the gypsey- molh, which abounds in the Netherlands, but is rare in most parts of Britain, we inclosed two or three in chip boxes. Upon opening these, a short time after- wards, we found that one of the moths had deposited a patch of eggs ; but, instead of the conical form which the insect would have chosen had she been at liberty, she had disposed them in the form of a wheel, of which her body was the radius. This, of course, was not so much to be wondered at, as it no doubt arose from her want of space to proceed in the usual manner ; but we deem it worthy of notice that this wheel, which was about a quarter of an inch broad in the rim, was sloped • female pynsey moth, one-third the natural size, just finish- ing her group of i-ggs. b, female gypsey moth, with its bodv covered with down, c, circle of eggs covered with hair, and d, conical mound of eggs covered with hair, laid by gypsey-motha in contincment. ;. R. |- Reaumur, Mem. ii., 101 F 5 82 INSECT TRANSFORMATIONS. with the greatest regularity, after the manner of a candle-shade, and the down tiled upon it all round. Another of our prisoners, though precisely in the same circumstances as to space, instead of forming- a wheel, piled up her eggs in form of a circular mound ; but as the number of her esgs was not a sixth part of those of the other, (probably from her having deposited part before we caught her,) this may have induced her to vary the shape of the group. Like the others, how- ever, the regular slope and tiling of the down was carefully preserved* We have now (April, 1S30) a numerous brood of caterpillars from these very eggs. The eggs, \yhich are thus deposited with so much care, are destined to abide all the pitiless pelting of the storms of winter ; for, although they are laid in August, they are not hatched till the elm comes into leaf in the following spring. The covering of down, accordingly, from the manner in which it is tiled and brushed smooth by the mother moth, not only protects them from wet, but from severe cold, being one of the best non-conductors of heat. The experiments of modern chemical philosophers have proved beyond a doubt, that the warmest material for clothing is not what imparts most heat to the body, but what best prevents tlie escape of the heat generated there. The feeling of cold, therefore, does not, as might be suj)- posed, arise from anything positively cold, but solely from a deficiency of heat. On putting the hand, for example, on a piece of ice, the feeling of cold does not arise from cold given out by the ice to the hand, but fiom the heat which the ice takes from the hand, which heat can be actually traced in the water formed by the melting of the ice. But when the hand is laid upon wool, feathers, or down, these do not feel cold, because they do not carry off the heat of the skin so rapidly as the ice. * J. R. PROTECTION OF EGGS. 83 it may appear a little paradoxical, though the doc- trine is sound, to assert that down and similar ma- terials are nearly as well calculated for protecting an animal from excessive outward heat as from severe cold. This, hovvever, has been long- well known as a fact to the Neapolitan peasantry, who convey snow from Mount Vesuvius to Naples in the summer for the purposes of luxury : they preserve it from melting by covering it with chaff and wool. It may not be out of plac« to remark that instances of this occur among insects, precisely similar to what we have just detailed respecting the gypsey-moth. The brown-tail and the golden-tail moths (Porthesia ai/rijlua, and P. Chry- sorrhma, Stephens), whose caterpillars spin them- selves a warm nest before the setting-in of the wint«^ colds*, seem no less careful to protect their eggs from the summer heats of July and August, at which time they are deposited. The down with which they are furnished for this purpose grows upon the tail of th«» female moth, in form of a thick tuft or brush, of a shining silky gloss, and of a different colour from the short hair on the body. It may be remarked that moths have only a mouth-tube for sucking honey, and Females of the brown and gold-tailed moths, showing the bunch of down on the tails. ♦ See ' Insect Architecture,' p. 329—331. 84 INSECT TRANSFORMATIONS. no mandibles or jaws*, like bees, wasps, and beetles, for perform! 112; any mechanical labour ; but the moths in question have an organ admirably contrived for covering their eggs with down. This consists of an extensile instrument, situated in the tail, not unlike the points of a pair of sugar-tongs, and intended to perform the part of tweezers in pulling off the down, and placing it upon the eggs. Having reared nume- rous broods of the moths alluded to, we can testify to the minute accuracy of Reaumur in detailing their proceedings. He remarks, that though the mother moth is exceedingly sluggish (lourde) in her general movements, she employs her tweezers with surprising quickness, on all sides, first to pull off a pinch of down, and spread it out, and then to place the egg upon it, and cover it neatly over, and smooth the down in the proper direction. The nature of the instrument will be better understood by the following figures. Tweezers of the brown and gold- tailed moths, magnified. Reaumur has figured the deposition of the eggs of an insect, the species of which is not ascertained, sent him by a physician of Lu9on, which are covered, like the preceding, with down, but are arranged in an elegant spiral form, as if a lady would wind one of the ends of her fur tippet spirally round a branch. * Savigny, however, has displayed much acumen in showing how the suckers of moths, &c., are analogous to mandibles. — Me- moires sur ks Anim. suns Vtrtcb. SPIRAL poRM OF EGGS. 85 These egg's were extremely small, and the down very fine, like the short fur of the beaver, and of a pretty squirrel-grey colour. The eggs were oblong, and placed on end, at right angles to the branch ; as was also their downy envelope, which differed in this respect from the imbricated and smoothly brushed coping of the moths above described. There is no- thing of this kind, says Reaumur, which we ought to consider it difficult for an insect to execute, when we are acquainted with the admirable instruments with which nature has furnished them*. Spiral group of eggs of an unknown moth. The spiral form of eggs deposited upon a branch may, in particular years, be seen in almost every orchard and every hedge, being the method followed by the lackey-moth \Clisiocampa neustria^ Ste- phens) and its congeners. The precise manner in which the mother lackey proceeds has not, so far as we know, been witnessed by any naturalist ; and though Reaumur reared a great number on pur- pose to discover it, all his efforts proved unsuccessful. An examination, however, of the arrangement of the eggs themselves, shows that they are placed in a manner excellently adapted to secure their adhesion to the branch, and to prevent their sustaining injury. The eg^ is somewhat of the form of a funnel-shaped wine-glass — broader at top than at bottomf; and it * Reaumur, Mem. ii. 107. 1 See two of these eggs figured iti * Insect Architecture/ p. 19. 86 INSECT TRANSFORMATtONS. is worthy of remark, that this is the precise form of tlie arch-stones of a bridge. They are, in fact, built tog-ether in the arched form. This, together with the strong cement employed in uniting them, renders it difficult to crush them, though considerable force be used for that purpose ; and this even when they are slipped off the branch, round which they are set like pearls on a bracelet, which is the name given them by the French peasantry. The cement, also, is so hard, that when pressed it resists the nail, though it may be pierced with the point of a sharp knife; and not being soluble in water, " nor in any other liquid," says Swammerdam, " which I have tried,'' the heaviest rain dashes upon the eggs without injury. Eggs of thelackcy-motb, wound spirally round a twig of haw- thorn ; natural size, and magnified. It may be a question with some, when they com- pare these naked eggs of the lackey-moth, exposed on a bare branch, with the warm downy covering of those of the gypsey-moth, how the former are protected from the colds of winter. This is a question which previous researches cannot fully answer, but one cir- cumstance is obvious — the lackey's eggs are many degrees harder than those of the gypsey, which may be easily crushed. Pro])ably also, this may be con- nected with their electrical state ; and that has always HYBERNATION OF EGGS. 87 an intimate connection with heat in aninnated bodies. The hving principle, to which we shall by and bye advert, must also be taken into account- In consequence of the minuteness of insect eggs, notwithstanding the researches of enthusiastic ento- mologists, we are still unacquainted with by far the greater number. The hybernation of eggs is, there- fore, a subject upon which little is known. In the egg state insect life is, perhaps, less liable to ac-cidents, than in a more advanced stage of existence ; and it is most probable that the greater number remain un- hatched during the cold season. Different modes of depositing eggs are resorted to by different species of the same genus, as may be exemplified in the plant- lice {Aphides). It was observed by De Geer, that those of the birch and the blackthorn {Aphu Alni, and A. Pruni) covered each egg individually with a white cottony down, detached from their bodies by means of their hind legs, and placed by the same means over the eggs*. But the greater number of this family lay their eggs in an exposed situation, upon the plants where the young, when hatched, may find food. Thus Kirby found the small black eggs of a large species on the buds of birch-trees; and we have just disco- vered (Jan. 1830) a numerous deposit of the eggs of the magpie plant-louse {Aphis Samhuci) on an elder tree, where the insect was abundant the preceding summer f. These eggs are exceedingly minute, but easily observed on account of their shining black colour. They are placed in an irregular patch upon a part of the trunk from which the bark has been stripped off, and are entirely unprotected. The cochenille insects (Coccidce, Leach), so called from one of the species furnishing the well-known valuable dye-stuff, protect their eggs in a still more * De Gecr, Mem. sur les Insecles, iii. 48, 51. t J. H. 88 INSECT TRANSFORMATIONS. remarkable manner. The mother deposits her eg:ij;8 under her body, which becomes glued to the spot ; she then dies, and her body becomes a covering for the eggs. In this state the insects appear on the bark of trees like small warts, some species in the form of a boat, some kidney-shaped, and others globular ; and, before their history was understood, they were with some plausibility supposed to be vegetable galls, — whencethey were termed Gall Insects hy the French. Though the mother insect is seldom larger than a peppercorn, the number of eggs which she lays amounts to several thousands, and in fact fills the greater portion of her body. Those which are found on our green-house plants, and which are the pest of the grape-vines in the neighbourhood of London, both in and out of doors, secrete a sort of white silky gum, very like gossamer, as the first bed of their eggs. Reaumur could not discover that the mother insect was furnished with any organ similar to those of spiders and caterpillars for spinning this gossamer ; and in an allied genus {Dorthesia)^ Kirby and Spence talk of it as " wire-drawn through nu- merous pores in certain oval plates in the skin*." Having minutely observed, during several successive summers, some thousands of the female cocci found on vines in the open air, we have satisfied ourselves that this cottony matter is precisely similar to the gluten which envelopes the eggs of most insects ; and that it is neither spun like the threads of cater- pillars, or the webs of spiders, nor wire drawn through numerous pores, — but is simply excluded along with the eggs. We may remark, also, that the covering formed by the body of the mother coccus prevents this substance from drying, as the webs of spiders do ; and, consequently, it can at any time be * Introd. iii., p. 183. EGGS OF THE COCCI. 89 drawn out into extended threads, by detaching a few of the eggs from the mass. Eggs of the Coccus covered with down, and with the bodies of the mothers. An account, which appears to us altogether apo- cryphal, has been given of the migrations of the species which produces the cochinelle {Coccus Cactiy Linn,). From the females remaining stationary, it is said, their numerous progeny would not find sufficient nutriment on their native tree ; and they are, at the same time, so delicate, that they could not travel along the ground from one plant to another ; Magiiiried cocln'i 111 eels, iCuccus cacti), a, Male, h, Female. 90 INSECT TRANSFORMATIONS. l)!it nature, it is alleged, provides for them admirable means of emigration, since, at the period of their birth, a multitude of spiders fasten their nets to the leaves of the nopal, and along these, which serve them for bridges, the young cocci emigrate to the adjacent trees*. We have little doubt that this story has originated in the inaccurate observations of some fanciful traveller, who mistook the threads acciden- tally drawn out from the mass of eggs, for those of a spider. The gossamer envelope, however, which we have just described as covering the eggs of the coccus that is common on our British vines, is not intended as a defence against the cold of winter ,» for this species hybernates, according to Re'aumur, in the larva state, though we have frequently searched for these larvae in vain during winter, on vines where they swarmed in myiiads during summer. But the British species of coccus of the hawthorn, &c., on account of which we introduced the subject here, assuredly hybernates in the egg state; and may be seen at the otf-goings of the branchlets in an oval form, like that of a minute wood-louse {Oniscus), of a silvery grey colour, differing, indeed, but little from the tint of the bark. On raising up with the point of a pen- knife what appeared to be the body of the insect, we found that it was hard, dry, and dead, — the mere skin, in a word, of the mother coccus, while under- neath was a multitude of eggs of a deep orange colour. It is worthy of notice, also, that there is, then, no envelope of gossamer, thotigh there is mixed up with the eggs a small quantity of a greyish white powder, which, we are inclined to conjecture, may be the dried remains of it; and, the more so, that Ueaunmr figures the gossamer as abundant in the coccus of the hawtln)rn. Unfortunately he lias not * Si. Pierre, Studies of Nature, vol. i. EGGS OF THE COCCI. 91 mentioned at what season he procured these, and we have no means of ascertaining whether our species is the same with his*. a b c. Eggs of the hawthorn coccus, covered by the body of the deiid mother, d, one of these magnified, e, a section, showing the eggs within. We have found the eggs just mentioned most abundant on the hawthorn in the hedges around London ; but as the size, the colours, and the forms of the crust are very different, there can be no doubt of there being' different species even on the same tree. "In July, 1812," says Kirby, "I saw a cur- rant-bush miserably ravaged by a species of coccus very much resembling the coccus of the vine. The eggs were of a beautiful pink, and enveloped in a large mass of cotton-like web, which could be drawn out to a considerable length t." From the manner in which this justly popular author speaks, it would ap- pear he had not elsewhere met with this coccus ; but ♦ I. R. t Intr. i. VJ7. 92 INSECT TRANSFORMATIONS, it is by no means of rare occurrence, and may be found on most currant-bushes, and often on hawthorns, &c. around London. The envelope of the eggs is of a chestnut-brown colour. A much more singular species occurs in company with the preceding, and abounds on the currant- bushes at Lee. From their resemblance to the form of one of the valves of a mussel-shell, Reaumur named this species en coquille (Coccus conchiformis^ Gmelin). He says, it imposed upon him for several years, as he supposed it to be the cocoon of some minute insect about to go into the pupa state; but he was undeceived by finding them full of eggs. We were more disposed, at first, to look upon them as a subcortical fungus (such as Cuciirbitaria Berberidisy Grev., or Cryptosph(eria Pteridis, Sowerb.), for, during the winter, when we first observed them, they appeared exactly like a little slip of the bark elevated by the growth of a fungus below it. Then they were so crowded on some branches, that not a hair's breadth of the bark remained uncovered. When, however, we found these minute bark-like scales full of eggs, we were iiiclined to conjecture that they had been depo- sited by saw-flies cutting into the bark ; but this was instantly disproved by removing them, and finding the bark below sound and uncut. Rt^aumur put the matter beyond dispute by actually hatching ihe eggs, when insects were produced similar to other cocci. But our species, found on the currant-bush, seems to differ from his of the elm, not in form and colour, but in habit, being gregarious, while his was subsolitary *. During the severe frost of 1829-30, we observed several small birds, such as the long-tailed titmouse {Parus cmidatus), and the gold crested wren {Regu- * J. R. DEPOSITIONS OF EGGS. 93 lus crislatus, Ray), busily pecking- the eggs of the cocci in the hedges *. The resemblance of these singular insects to the wood-louse (Oniscus)^ which is not properly an in- sect, but a crustaceous animal, may be traced farther than mere external appearance ; for the body of the mother, in the latter, also becomes a covering for the egg, though she does not die immediately after laying as the coccus does, but carries her eggs under her breast in small four-valved cells. One of the most easily discovered depositions of eggs during the winter months are those made by various species of spiders, particularly that of the large garden-spider {Epeira diadema), which may be found in the angles of walls, in form of a ball, about the size of a cherry, of beautiful yellow silk, and much stronger than the common materials of the same spider's geometric web. This substance Reaumur endeavoured to bring into use as a substitute for silk; but he was unsuccessful in procuring it in quantity, owing to the ferocious habits of the spiders, which devoured one another when he reared them gregariously. As the eggs of spiders have usually a thin soft shell, a thick warm envelope of silk is, no doubt, essential to their weathering the colds of winter, notwithstanding the sheltered corners where they are usually placed. Some species weave these little silken nests in a very elegant form. We possess one of the pyriform shape of a balloon, the texture of which is close and netted with diagonal meshes. One, somewhat in form of a drinking-glass, is figured in Loudon's Magazine of Natural History, as having been found near Wandsworth, attached to the stem of a rush growing in w ater. There was a deposition of eggs at the bottom, the rest of the space being vacant. De Geer describes -* J. R. 94 INSECT TRANSFORMATIONS. similar spiders' nests attached to the stems of g'rass *; and we once found a large one of an elongated shape, and composed of very white silk, on a spike of grass at Compton-Basset, VViltshiref. Spiders' nests. The vapoiirer {Orgyia antiqua, Ochsenh.), a com- mon moth, takes advantage of the warm silken enve- lope of the pupa-case, from which she has escaped a few days before, to form a bed for her eggs. In our earlier studies of insect economy we were inclined to ascribe to accident the deposition of the eggs in this particular situation, but we have found so many instances of it as to reject the explanation. Swam- merdam also observes, that " this custom of fastening the eggs to the web is a constant method, and by the immutable law of nature, is so peculiar to this species of insects, that I have never ob- served it in any other kind whatsoever. This female," he subjoins, " like a most prudent house- wife, never leaves her habitation, but is always fixing her egg^ to the surface of the web out of which she has herself crept, thus affording a beau- tiful instance of industrious housewifery J." One * De Geer, Mem. vol.vii. pp. 227-9. f J. R. X Swammerdaui> ;it. ii. p;ige 7. DEPOSITIONS OF EGGS. 95 reason for this is, that the female of this motii havini^ only the rudiments of vving-s, a peculiarity remarkable in several other moths, she cannot shift so readily about. But whatever may be the real cause, there can be no doubt that the web serves to keep the eg-gs warm during winter ; for though they are placed on the outside of the web, the whole is usually under some projection of a wall or arm of a tree, and the non-conducting property of the silk, both with regard to heat and electricity, must be of great benefit to the eggs in preserving them in an equable temperature, and of course promoting their early hatching. "^'ii^M^-' Vapourer-moth {Orgym antiqua'), male and female, the latter without wings; with the eggs laid upon the silken cocoon from which the mother has issued. We cannot better conclude these imperfect sketches of the hybernation of insect eggs, than by an ac- count of the ingenious experiments made by Spallanzani and John Hunter, by exposing several species of these to great degrees of cold as well as of heat. It results from these experiments that " intense cold," to use the words of Spallanzani, '• does not destroy the eggs of insects." The year 1709, when Fahrenheit's thermometer fell to 1° is celebrated for its rigour and its fatal effects on plants and animals. Who can believe, exclaims Boerhaave, that the severity of this winter did not destroy the eggs of insects, especially those exposeil to its iniluenre- in the open fields, on the naked 96 INSECT TRANSFORMATIONS. earth, or on the branches of trees? Yet, when llie spring had tempered the air, these eg:g's produced as they usually did after the mildest vvinters. Since that period there have been winters more severe. In France, during December, 1788, the thermometer fell considerably lower, and in several other tempe- rate European climates. " I have exposed eij^gs to a more rigorous trial than the winter of 1709. Those of several insects, and among others the silk-worm, moth, and elm- butterfly {Vanessa polychloros?) were inclosed in a glass vessel and buried five hours in a mixture of ice and sal gem {rock salt) ; the thermometer fell 6® below zero. In the middle of the following spring, however, caterpillars came from all the eggs, and at the same time as from those that had suffered no cold. In the following year I submitted them to an experiment still more hazardous. A mixture of ice and sal gem with the fuming spirit of nitre {Nitrate of AmmonkOy reduced the thermometer 22° below zero, that is 23° lower than the cold of 1709. They were not injured, as I had evident proof by their being hatched. '• Combining all these facts, we conclude that cold is less noxious to germs and eggs, than toanimalcula and insects. Germs in general can support 2° below zero; whereas of animalcula some die at the freezing point, and some at about 20° The eggs of many insects continue fertile after being subjected to a temperature of 22° below zero, while insects themselves die at 16° and 14°. This I have ascer- tained in the eggs of the silk-worm moth and of the elm-butterfly; and although there are caterpillars > and chrysalides able to resist great cold, I have uni- formly found it to be in a less degree than what cam be resisted by their eggs. What can be the cause ofl sc great a difference? Insects killed at lG°and 14°' EFFECTS OF COLD UPON EGGS. 97 are so penetrated and frozen by the cold, that their members do not yield to the pressure of the finger, and seem perfect ice under the knife. This does not happen to eggs, though subjected to cold of much greater intensity. Their contents remain fluid, even at the greatest cold, as may be seen by crushing them with the nail. Perhaps this is derived from constituent spirituous or oleaginous parts, or from some principle adapted to abate the power of cold *. If eggs do not freeze, it is probable the included embryos do not freeze. Is there anything won- derful, therefore, that they then survive cold which is fatal to them when produced? Probably for the same reason (and I see no objection that can apply), animalcula, concentrated in the germ, can support a degree of cold they are incapable of when developed. '* As the temperature of freezing still retains a portion of heat, why, it may be asked, should it not develope the germs of the most minute animalcula? Had we never seen any eggs hatched but those of birds, which require 104°, we should have concluded that all others require the same. A little initiation into the study of minute animals teaches how many kinds produce at a temperature infinitely less. Such are the eggs of butterflies and many other insects, of frogs, lizards, tortoises, down to some, as those of toads, which 1 have seen produce at 45*^. If these eggs hatch at 59° less than is required by those of birds, what repugnance will there be to suppose that at 13° less, or th(* freezing point, the eggs of other animals may be hatched? Nor should it surprise me to be tcld of animals whose eggs would produce at much greater cold, after knowing that there are plants, beings so similar to animals, and many of Ihem, * In plain language, Spallanzani did nut know what to make ol the facis. G 9S INSECT TRANSFORMATIONS. which amidst the rigours of winter flourish and fruc- tify*" It is remarked by John Hunter that an egg will freeze by a great degree of cold ; at the same time there seems to be a living principle which enables it to support cold without destruction, and when once that principle is destroyed, cold more easily operates. An egg was thus frozen by the cold of zero ; after thaw- ing and again exposing it to the same degree of cold, it froze seven minutes and a half sooner. A new-laid egg took an hour to freeze in 15° and 17°, but when thawed, it froze at 25° in half the time f- The principle of vitality, therefore, whatever may be the cause, is evidently less easily destroyed in the egg state than in the perfect animal ; and therefore the inference that a rigorous winter promises a diminution of insects in the summer succeeding commonly proves erroneous. On the contrary, recorded facts prove that they are sometimes even more abundant than usual after severe frosts. During the present spring of 1830, accordingly, notwithstanding the severe frosts of the preceding winter, we have observed a nnich greater number of insects, even of the smaller and more delicate kinds {Akyrodcs, Corethra, Ahicita^ &c.) as well as of larvae, both those just hatched, and those which have lived through the winter, than last year, when the frost was not so severe. We were particularly struck with the larva? of some small tipula (Boletophila?), which we found in abundance in Birch Wood, Kent, feeding on a fungus {Bohtua JhnicntarmSj P'ries), and which were so beautifully transparent and soft, that we could not understand how they had escaped being frozen. It is not a little remarkable, in connexion with this, that the * Spallarizani's Tracts, transl. by Dalyell, v()I. i. p. o3. f Hunter on the Anima! Economy. EFFECTS OF COLD UPON INSECTS. 99 migratory birds seem to have been aware of tliis abundance of insects by tlieir appearing earlier than usual. We saw a pair of nightingales at Greenhithe on the 21st of March, and a number of swallows the same week at Lee, — which is two or three weeks be- fore their average time *. *J. R. 100 Chapter V. Hatcliing of Insect Eggs The contents of an egg principally consist of nutri- ment adapted to the different parts of the germ which it contains — the yolk for nourishing; the soft parts; tiie white, for the blood and other fluids; and the shell, for the bones. In the case of insects, as well as of birds, fishes, and reptiles, the embryo is placed in the most advantageous j-osition for par- taking of the repast, — namely, in a particular corner where it may breathe fresh air always communicated to the chamber of the egg by ventilatory passages in the shell ; if these be shut up, by covering the egg with grease, varnish, or chalk, it is suffocated and dies. In the case of birds, according to Malpighi and the older physiologists*, the rudiment of the chick, while still a minute point, is lodged on the film that envelopes the yolk, near the centre of the egg ; and, — as the floating wick of a mariner's lamp is constantly preserved upon a level u ith the surface by the mobility of the slings and the weight of the oil-vessel tending downwards, however the ship move, — there is an ingenious natural mechanism, which prevents the embryo chick from being upset when the egg is stirred. The yolk is sustained by two membranous ribbons, visible at the aperture of the egg, and fastening it on each side to the common membrane glued to the shell. These suspensory bands being fixed above the centre of the yolk, of * M;ilpi<;lii, (ie(Uo iiicuUato; Lceuweiihoeck, Epist. phys. xl. ; a«)d Hiuvey, in Willughhy's Ornilliol. c. ill. HATCHING OF EGGS. 101 course the more weighty part always descends, in every position of the egg, as far as they uill permit, and the chick being thence prevented from sliding down, nourishes itself in security. We cannot, on account of their minuteness, ascer- tain whether there is any similar mechanical contriv- ance in the eggs of insects ; but we have in several instances distinctly observed the speck where the embryo insect was placed just within the shell of the egg. In order to stimulate it to feast and fatten on the good things stored up in his egg-shell chamber, it appears that a certain degree of heat is indispensably requisite ; for cold, though it does not usually, as we have seen, kill the embryo, almost always renders it torpid. But the stimulus of heat produces activity in the living principle, causes the embryo to devour all the nutritive contents of the egg, and thence to increase proportionably in size. It is worthy of remark, however, that the stimulus of light, contrary to that of heat, acts unfavourably upon the hatching of eggs. Both of these positions may be illustrated by numerous facts and experiments. Most birds, so far as has been ascertained, supply the heat necessary for hatching their eggs by sitting constantly upon them during a certain number of days ; but reptiles, such as the crocodile, bury their eggs in the warm sand upon the banks of rivers. I Insects, again, seldom, if ever, sit upon their eggs, as birds do, in order to hatch them. This, indeed, would be impossible, as the greater number of insects die in a few days after depositing their eggs, the con- tinuation of the species being apparently their only business in their last or perfect stage; since, as they Ithen generally cease to feed, they cannot possibly live i long. A few instances, however, have been observed, of insects performing something very similar to the g3 102 INSECT TRANSFORMATIONS. incubation of birds, though we have the hig^i authority of Fabricius, that " insects never sit upon their eggs*." Upon the incontestable statements of two dis- tinguished observers of insects, Frisch f and De Geer, the female of the common earwig (Forjicula aunci/laria, Linn.) sits upon her eggs. This circumstance, however, seems to have escaped the notice of other naturalists, though her attentions to her young ones is often witnessed. De Geer disco- vered a female earwig in the beginning of April under some stones, and brooding over a number of eggs, of whose safety she appeared to be not a little jealous. In order to study her proceedings the better, he placed her in a nurse-box filled with fresh earth, and scattered the eggs in it at random. She was not long, however, in collecting them with all care into one spot, carrying them one by one in her mandibles, and placing herself over them. She never left them for a moment, sitting as assiduously as a bird does while hatching. In about five or six weeks the grubs were hatched, and were then of a whitish colour |. At another time, in the beginning of June, De Geer found under a stone a female earwig accompa- nied with a numerous brood of young, to all appear- ance newly hatched, and nestling under their mother like chickens under a hen. These he likewise placed in a nurse-box with fresh earth; but instead of burrow- ing into the mould, as he had expected, they crowded under the bosom and between the legs of their mo- ther, who remained quiet and evidently pleased, suf- fering them to continue there for an hour or more at a time. He fed both this brood and the one first mentioned with bits of ripe ix\)^)\e ; and perceived that * Fabricius, Philosoph. Erilomol. Ixxvi. t liisecten in Deutschland, 4to. 1766. I De Geer, Mem., vol. iii. p. 518. HATCHING OK EGGS. 103 tt>€y grew from day to day, and cast their skins, as caterpillars do, more than once. The mother did not live long', probably in consequence of confinement ; and her progeny devoured nearly the whole of her body, as they also did the bodies of their brethren, when any of these chanced to die. We may remark, in passing, that it is an unfounded popular prejudice that earwigs get into the brain by creeping into the ear; for though, from being night insects, and dis- liking exposure to the light, they may, by chance, attempt to take shelter in the ear, the disagreeable odour of the wax will soon drive them out: at all events they could never get farther than the drum, which completely shuts the passage to the brain. We have known, indeed, a small beetle get into the ear ; but it did no further injury than produce a strange tingling sensation by crawling about the drum, and soon made its exit*. A little red insect (the harvest-bug?) sometimes gets into the ear in bed, and produces wonderful commotion ' •'* no real injury. Drum of the ear, shovving that there is no passage through it to the brain. Kirby and Spence are inclined to infer that a tree- bug {Acanthosoma grlsca, Stephens) may also sit ♦ J. R. 104 INSECT TRANSFORMATIONS. upon its eg'g's*, because De Geer found a mother of this species surrounded with a brood of thirty or forty young' ones following' her as chickens follow a hen. She never leaves her family ; but as soon as she moves, all the young ones closely follow, and assem- ble arotmd her in a cluster wherever she makes a halt. De Geer once cut a branch of birch, upon which a family of these bugs had assembled, and the mother showed every symptom of fear and distress. Had she not had a family to protect, she would have taken immediate flight ; but instead of this, she kept beat- ing her wings rapidly and incessantly, and never stirred from her young. But even all this, affection- ately maternal as it must be considered, is far from authorizing the conclusion that she sits upon her eggs ; thong-h it is certain she must remain near them till they are hatched, unless she belong to those men- tioned by Busch as ovo-viviparous f. One of the most common instances of something similar to birds hatching their eggs occurs in several species of spiders, which may be seen sitting near or upon the silken bag in which they have inclosed their eg-gs. Many of these mothers, however, die before their young are hatched, — all of them, perhaps, when the eggs are laid late in autumn. During the winter of 1829-30, we watched a considerable number of the geometric spiders {Epeirce) brooding over their eggs for several weeks; but though the weather before Christmas was litlle more than an average decree of coldness, every one of them died, some living a longer time, and others a shorter |. But this is not the case with a very common wandering spider called by Dr. Lister the wolf {Lycosa saccata, Latr.), and first observed, we believe, by the celebrated Har- vey §. " In order," says Swammerdam, *' to hatch * Intro, i.358, and iii. 101, I Schneider, Europiiische Schmctterlinge, i. 206. ;* J. R. § Harvey, De Generatioiie. HATCHING OF EGGS. 105 her eggs tlie better, she carries them about as it were in a case, with wonderful solicitude and affection; insomuch, that when the skin forniin<^ this case, which hangs to the hinder part of lier body, is by any acci- dent broken off, the Httle insect seeks after it with as much earnestness and industry as a iien for her lost chickens, and when found fastens it again to its place with the greatest marks of joy *." Bonnet has given a more detailed account of the manners of this spider, which, though no less fierce and ferocious in aspect than her congeners, mani- fests an extraordinary change of mien when forcibly deprived of her eggs. Then she instantly appears I tame, stops to look around her, and begins to walk at I a slow pace, and search on every side for what she [ has lost, nor will she even fly when one threatens i to seize her. But should the experimenter, moved with compassion, restore her bag of eggs, she catches it up with all haste, and darts away in a moment; or, when left undisturbed, will leisurely attach it again j to her body. " With a view," continues Bonnet, " to put this 'singular attachment to a novel test, I one day threw a spider with her eggs into the pitfall of an ant-lion {My rmelion formicariuiri)'\ . The spider endeavoured to escape, and was eagerly remounting the side of the pit, when I again tumbled her to the bottom, and the ant-lion, more nimble than the first time, seized the bag of eggs with its mandibles, and attempted to drag it under the sand. The spider, on the other hand, made the most strenuous efforts to keep her hold, and* struggled hard to defeat the aim of the concealed depredator; but the gum which fastened her bag, not being calculated to withstand such violence, at length gave way, and the ant-lion was * Book of Nadiro, j)t. i. p. 24. <■ See Insect Archittclu'Cj p. 209. 106 INSECT TRANSFORMATIONS. about to carry off the prize in triumph. The spider, however, instantly re^iained it with her mandibles, and redoubled her endeavours to snatch the bag from her enemy ; but her efforts were vain, tor the ant-lion, being the stronger, succeeded in dragging- it under the sand. The unfortunate mother, now robbed of her eggs, might have at least saved her own life, as she could easily have escaped out of the pitfall ; but, wonderful to tell, she chose rather to be buried alive along with her eggs. As the sand concealed from my view what was passing below, I laid hold of the spider, leaving the bag in the power of the ant-lion. But the affectionate mother, deprived of her bag, would not quit the spot where she had lost them, though I repeatedly pushed her with a twig. Life itself seemed to have become a burden to her since all her hopes and pleasures were gone for ever*" That some i)ortion of heat may be communicated to the eggs of the spider, which are thus carried so assiduously under her body, is highly probable ; and it is also, no doubt, advantageous to the young, when hatched, to have the assistance of their mother to open the bag for them, as was remarked by De Geert; *' without which," say Kirby and Spence, " they could never escape J." But that neither of these are indispensable conditions we have ascertained by re- peated experiments. We have taken a considerable number of these egg-bags from their mothers, and put them under inverted wine-glasses and into pill- boxes, and in every instance the young have been duly hatched, and made their way without assistance out of the bag. In all these experiments, the young spiders joined in concert in making a web across their prison ; a circumstance at variance with the assertion, * Bonnet, CEuvrcs, vol. ii. p. 435. t Do Geer, Mem. vol.vii. p. 11)4. X Iiitrod. i. p. 361, HATCHING OF EGGS. 107 copied from Lister into most subsequent works on natural history, that this species never spins a web. They might not indeed have done so if they had b^en left at liberty *. A spider of the same species, which Bonnet kept under an inverted glass, at first was so exceedingly attached to her bag of eggs, that he could not beat her away from it after it was detached. " By and bye," he continues, '' I observed with surprise that she iiad abandoned and kept aloof from the very bag which she had previously defended with so much courage and address ; and I marvelled still more to see her run away from it when I placed it near her. I remarked at the same time that she had become less agile, seemingly in consequence of sickness. By more close observation, I discovered that several of the young ones were hatched, and their numbers increased by degrees, while all ran towards their mother and climbed upon her body. Some placed themselves on her back, some on her head, and some on her limbs, so that she was literally covered with them, and appeared to bend under the weight, not so much from luing over loaded, as from her feeble con- dition ; and indeed she soon afterwards died. The young spiders remained in a group upon the body of their mother, which they did PiOt abandon for some time, and for the purpose, as I was half inclined (par- don the odious supposition) to think, of sucking the juices of her body -f-." In order to prove whether a spider of this species could distinguish her own egg-bag from that of a .•stranger, we interchanged the bags of two individuals, whicii we had put under inverted wine-glasses ; but both manifested great uneasiness, and would not touch the strange bags. We then introduced one of the mothers into the glass containing her eggs and * J. R. t Bonnet, (Euvres, vol. ii. p. 440, 108 INSECT TRANSFORMATIONS. the Other spider; but even then she did not take to them, which we attributed to the presence of the other, as all spiders nourish mutual enmity. Upon remov- ing the stranger, however, she showed the same indif- ference to her eggs as before, and we concluded that, after having lost sight of them for a short time, she was no longer able to recognize them *. A more extraordinary method of batching eggs occurs in several insects, thence termed ovo-vivipa- rous, which retain the eggs within their bodies till they are hatched ; and in this way they appear, like larger animals, to produce young instead of eggs. We do not here allude to the cochenille insects formerly mentioned ; for though these cover their eggs with their bodies, it is after they are laid and imbedded in gossamer. Neither can these singular insects be properly said to sit upon their eggs, inasmuch as the mother always dies when she has finished laying. Tlie guffer (Blennius ovo-viviparus, Lacepede), a British sea-fish, common under stones at low-water mark, affords an instance of this singular mode of the eggs being hatched in the body of the mother ; and it is remarkable that when the young are ready to appear, she leaves her usual haunts on the coast, and goes fartlier out to sea, that they may be out of the reach of thtir natural enemiesf. Ourcommon viper {Coluber bents, Linn.) is also ovo-viviparous, as are several other reptiles; though it is an exception to the general rules in this class. We caught a female of the nimble lizard (JLacerta agilis, Linn.) on a heath near Sorn, Ayr>hire, in July, and kept it for some time under a glass, where it produced six young ones ; but in consequence of improper food, or of confinement, they all soon died J. This lizard is said to be some- times oviparous. The observations also of the elder li ♦ J. R. f Lacepede, Poissons, ii. p, 497. J J. R. I OVO-VIVIPAROUS INSECTS. 109 naturalists with respect to the scorpion's being ovo- viviparous, have been recently verified by Leon Duibur*, a living French naturalist, distinguished for acuteness and accuracy. In the case of insects, it was first discovered by Redi, the father of experimental entomology, that, though the greater number of flies lay eggs, some also bring forth their young alive, and he was tlience led to put the question, whether such flies, under dif- ferent circumstances of temperature, do not sometimes produce young, and at other times deposit eggsf. He might as well, says Reaumur, have asked whe- ther, in certain circumstances, a hen, instead of laying- eggs, should bring forth chickens. The fact, on the contrary, has been ascertained by Reaumur, and re- cently confirmed by Dufour J, that the ovo-viviparous insects are furnished with an abdominal pouch, in which the eggs are deposited by the mother previous to their being hatched. In this respect they afford a striking analogy with the kangaroo, the opossum, and other marsupial quadrupeds, which are furnished with a similar pouch for protecting their young in the first stage of their existence. One of our most common flies exemplifies this. It may not have occurred to many of our readers that there are more sorts than one of the large flies usually called blow-flies and flesh-flies. One of these, distinguished by its brilliant shining green colour and black legs {Musca Ccssar, I^inn.), we have adverted to§ in recounting the experiments of Redi ; another, frequently called the blue-bottle {Musca vomitoria, Linn.), is easily distinguished by the abdomen being of a shining blue, the shoulders black, and the forehead fox-coloured. The insect, however, to which we wish to call attention at present, though nearly the size of the * Nouv. Diet. d'Hist. Nat. xxx. 426, f Redi, Esperienze intorno alia Gen. degl' Insetii, 4lr«. 1668. % Annales des Science? N;itiirclk'«. o Pa<:f» 3. 110 INSECT TRANSFORMATIONS. blue-bottle, rather longer and more slender, and black, with lig'hter stripes on the shoulders, is not blue in the ubdomen, but greyish black, and all over chequered with squares of a lig-hter colour. This chequered blow- fly {Sarcophaga carnaria, Meigen) does not even belono- to the same genus as the preceding', and differs from it in the remarkable circumstance of hatching its eggs in an abdominal pouch, and instead of eggs depositing maggots upon dead carcasses. The eggs of all the flesh-flies are in sultry weather hatched with great rapidity; but in the case of the chequered blow- fly, Nature has provided the means of still more rapid destruction for removing the ofFensiveparts of carcasses. The arrangement of the numerous minute larvse iu the pouch is very remarkable, and resembles the coil of a watch-spring, or a roll of ribbon. Reaumur had the patience and perseverance to uncoil this mul- titudinous assemblage of flies in embryo, and found it about two inches and a half in length, though the body of the mother-fly herself was only about one- A, tlie chequered blow-fly. B, the abdomen of the chequered >low-fly, opened and nja^nified, showing the coil of young larvae. C, the coil of lu'vx partly unwound OVO-VIVIPAROUS INSECTS. Ill third of an inch, and he computed that there were about 20,000 young in the coil*. When this extra- ordinary fecundity is considered, we need not wonder at the countless swarms which appear as if by magic upon a joint of meat during hot weather. Like most female insects, the mother-fly dies in a few days after giving birth to her numerous brood ; but, iHilike the oviparous flies, she seems to take a considerable time to deposit the whole. It would be impossible indeed for her pouch to contain the larvae if they were all hatched at the same time ; and there- fore it has been so ordered by Providence that they should arrive at maturity in succession. From the early death of the mother, Reaumur conjectured that they did not scruple to eat their way through her bowels ; but he disproved his supposition by a most decisive experiment. He took a fly which had already deposited a few larvse, and closed the natural opening of the pouch with sealing-wax, so that it was impos- sible any more could make their exit there. The mother lived several days longer than she would have done, had she been left at liberty to produce her young; but not one of them attempted to force a passage, after being slmt up for ten days. Another large grey fly with brick-red eyes (species A B A, large grey blow-fly, with the abdomen opened, showing the young maggots. B, breathing apparatus of the maggot of a large grey blow-fly. * Reaumur, Mem. iv. 417. H 2 112 INSECT TRANSFORMATIONS. not ascertained) was discovered by Reanmur to be ovo-viviparons ; but the embryo flies were not ar- ranged in the pouch in the same spiral form as the preceding, but longitudinally. These did not appear to be quite so numerous ; and they had a peculiar breathing apparatus, which, when shut, as it could be at pleasure, appeared in the form of a crown. Amongst several other ovo-viviparous flies dis- covered by Reaumur, there was a very minute tipu- lidan-gnat (species not ascertained) with a jet-black body, white wings, and beaded antennae, not larger than the head of an ordinary pin, which was bred in great numbers from some cows' dung put into one of his nurse-boxes for another purpose. He justly remarks upon this circumstance, that " the minute and the grand are nothing, or rather are the same, to the Author of Nature." The numerous genus Ajjhis presents the singular anomaly of producing eggs in the autumn and liv- ing young during sumn.er, and, as Curtis tells us, even during winter in green-houses. De Geer, how- ever, ascertained that it was not the same individual aphides which at one season produced young, and at another eggs, but different generations *. By a series of very careful and troublesome experiments, Bonnet also ascertained the curious fact, that in three montiis nine generations of these insects may be produced in succession, though the males be rigorously excluded from the nurse-boxes where the females are isolated. In fact, all the aphides produced in spring from the eggs laid in autumn, appear to be females; and no , males are produced till the end of summer, a short time before the eggs are deposited for winter. Among both males and females are some with and some without wings, — the nature of which distinction does not appear to be yet ascertained. * De Geer, Mem. des Tnsectes, iii. 70. EGGS OF APHIDES. 113 Bonnet, however, whose opinion is entitled to con- siderable authority, seems to think that the eg-gs of aphides which are destined to survive the winter are very different from other eggs ; and he supposes that the insect, in a state nearly perfect, quits the body of its mother in that covering; which shelters it from the cold in winter, and that it is not, as other germs are in the eg-g, surrounded by food, by means of which it is developed and supported. It is nothing more, he conjectures, than an asylum of which the aphides appearing at another season have no need ; and it is for this reason that some are produced naked, and others enveloped in a covering. If this be correct, the mothers are not then truly oviparous, even in autunm, when they deposit these pseudoeggs; since their young are almost as perfect as they ever will be, in the asylum in which they are naturally placed at birth. It was in vain that Bonnet endeavoured to preserve eggs of this sort in his chamber till spring, in conse- quence, he imagines, of the want of a certain degree of moisture, which they would have had out of doors. We have been more successful, through the precaution of not taking the eggs from their native tree till Febru- ary, and in 1830 we had a brood of several hundreds produced of the oak aphis {Aphis Quercu.s) *. The failure on the jjart of Bonnet leads us to re- mark, with the younger Huber, that ants are more skilful in this respect than naturalists, and anxiously nurse, during winter, the eggs of aphides, which they collect with great care in the autumn. The interest- ing narrative of the discovery of this we shall give in Ruber's own words. " One day in November," says he, " anxious to know if the yellow ants {Formica Jiarci) began to bury themselves in their subterranean chambers, I destroyed, with care, one of iheir habitations, story by * J. R. 114 INSECT TRANSFORMATIONS. story. I had not advanced far in this attempt, when I discovered an apartment containing an assemblage of httle eggs, which were for the most part of the colour of ebony. Several ants surrounded and ap- peared to take great care of them, and endeavoured, as quickly as possible, to convey them from my sight. I seized upon this chamber, its inhabitants, and the treasure it contained. " The ants did not abandon these eggs to make their escape ; a stronger instinct retained them : they hastened to conceal them under the small dwelling which I held in my hand, and when I reached home, I drew them from it, to observe them more attentively. Viewed with a microscope, they appeared nearly of the form of ants' eggs, but their colour was entirely different ; the greater part were black ; others were of a cloudy yellow. I found them in several ant-hills, and obtained them of ditferent degrees in shade; they were not all black and yellow ; some were brown, of a slight and also of a brilliant red and white ; others were of a colour less distinct, as straw colour, greyisli, and I remarked that they were not the same colour at both extremities. *' To observe them more closely, I placed them in the corner of a box faced with glass ; they were col- lected in a heap like the eggs of ants ; their guardians seemed to value them highly; after having visited them, they placed one part in the earth, but I witnessed the attention they bestowed upon the rest; they ap- proached them, slightly separating their mandibles ; passed their tongue between each, extended them,then walked alternately over them, depositing, I believe, a liquid substance as they proceeded. They appeared to treat them exactly as if they were eggs of their own species ; they touched them with their antennae, and frequently carried them in their mouths ; they did not quit these eggs a single instant ; they took them CARE BY ANTS OF EGGS OF APHIDES. 115 up, turned them, and after having surveyed them with affiictionate regard, conveyed them with extreme tenderness to the Uttle chamber of earth I had placed at their disposal. They were not, however, the eggs of ants ; we know that these are extremely white, be- coming" transparent as they increase in age, but never acquire a colour essentially different. I was, for a long time, unacquainted with the origin of those of which I have just spoken, and by chance discovered they contained little aphides; but it was not these individual eggs I saw them quit ; it was other eggs which were a little larger, found in the nests of yellow ants, and of a particular species. On opening an ant- liill, I discovered several chambers containing a great number of brown eggs, of which the ants were ex- tremely jealous, carrying them with the utmost expe- dition to the bottom of the nest, disputing and con- tending for them with a zeal which left me no doubt of the strong attachment with which they regard them. *' Desirous of conciliating their interests, as well as my own, I took the ants and their treasure, and placed them in such a manner that I might easily observe them. These eggs were never abandoned. The ants took the same care of them as the former. The fol- lowing day I saw one of these eggs open, and an aphis fully formed, having a large trunk, quit it. I knew it to be a puceron of the oak : the others were disclosed a few days after, and the greater number in my presence. They set immediately about sucking the juice from some branches of the tree I gave them, and the ants now found, within their reach, a recom- pense for their care and attention. The ant-hill whence these eggs had been taken was situated at the foot of an oak, which readily accounts for their existence in that place. 1 discovered them in the spring ; the pu- cerons which quitted them were very large for insects 116 INSECT TRANSFORMATIONS. just born, but they had not yet obtained their full size*." It is not, however, the aphides thempelves who select the snug winter retreat of an ant-hill, or who know how to secure the careful nursing of the ants. All this is the sole concern of the latter, to secure for them- selves a supply of the honey-dew, as it is erroneously called, secreted by the aphides in spring. The ants, it may be proper to remark, take similar care of their own eggs (as well as of their cocoons, popularly sup- posed to be their eggs), as was remarked by Sir E. King, in the reign of Charles II. He informs us that they diligently gather together in a heap their true eggs, which are small and white like the granules of lump sugar, and upon these eggs they lie in multi- tudes, " I suppose,'' says Derham, " by way of in- cubation -j-.'* '^ I have observed," adds Sir E. King, " in summer, that in the morning they bring up those of their young called ant-eggs {cocoo7is) towards the top of the bank, so that you may, from ten o'clock till five or six in the afternoon, find them near the top, — for the most part on the south side. But towards seven or eight at night, if it be cool or likely to rain, you may dig a foot deep before you can find them J." An interesting family of two-winged flies {Hip- poboscidcB, Leach) resemble the aphides in some points of their economy, though in others they are singularly peculiar. Reaumur discovered, what has been recently confirmed by Dufour and others, that the mothers not only hatch their eggs within the body, but retain them there till they are changed into chry- salides. Reaumur gives a lively narrative of his discovery, and the solicitude of his servants to find him female flies ready to deposit what he at first took for * M. P. Huber on Ants, p. 245. t Derham, Phys. Theol. ii. 207. lllh ed. J Pliil, Trans No. xxiii. OVO-VIVIPAROUS FLIES. 117 eggs. He was so anxious to hatch those supposed eggs that he carried them in his pocket by day and took them to bed with him at night, (as Bonnet afterwards did with the eggs of aphides,) for several weeks successively ; but instead of grubs, as he had expected, perfect flies were evolved exactly similar to their parents. He calls them spider-flies, from their resemblance to spiders ; and in some parts of France the species which infests horses {Hippobosca equina) is called the Spaniard or Breton : in England it is too well known under the name of the forest-fly. Spider-flies (^Hippohoscidce, I.eaoh). We have the more willingly introduced this sub- ject here, that another fly {Craterina Hirundinis, Olfers), of the same family, has the instinct to de- posit its egg-like cocoons in the warm feathery nest of swallows, where they have all the necessary heat which Reaumur, in his experiments, was so careful to maintain. In return for the warmth which the young has thus received, the perfect fly, during its brief existence, lives by sucking the blood of the swal- lows, as the one first mentioned sucks the blood of horses, horned cattle, and, it is also said, of man. h5 118 INSECT TRANSFORMATIONS. The effect of heat upon the eggs of insects has been carried much farther than in the experiments just alhided to of Reaumur and Bonnet*. Spallanzaiii was desirous of ascertaining what degree of heat the eggs of insects and other animals, as well as the seeds of plants, would bear when compared with their larvae ; and he found that below 93° Fahr. silk-worms did not appear affected, but at 95°, and still more at 97°, they became restless, while at 99° they ceased to move, and all died at 108°. The eggs of these, on the other hand, long resisted the influence of heat. At 80° they were the most productive ; at 99° many still appeared, but with considerable diminution, and as the heat was increased their fertility decreased, till at 144° not one was fertile. The eggs and caterpillars of the elm-butterfly (^Vanessa j)olychloros ?) perfectly corresponded with those of the silk-worm. In the case of the eggs of the blow-fly (^Musca vomitoria) a great many produced maggots at 124°; but at 135° and 138° very few, and all were sterile at 140°. The maggots produced from these eggs became restless at 88°, and endeavoured to escape, and as this heat was increased they became proportionably more agitated till it arose to 108°, when they all perished. Full- grown maggots of the same kind all died at 108°; but when changed into flies they died when the heat was so low as 99° ; though their pupee were produc- tive at 104° and 106°, but not at llPf- If these experiments may, as we believe they may, be relied on, we have some reason to doubt that " the eggs of the inusca vomitoria^ our common blow-fly, are often," as Dr. Good affirms, " deposited in the heat of summer upon putrescent meat, and broiled with such meat over a gridiron in the form of steaks, in a heat not merely of 212°, but of three or four times 212°; and yet, instead of being hereby destroyed, we * See Insect Architecture, p. 24. t Spallanzani, Tracts by DalyelJ, vol. i. p. 35. EFFECTS OF HEAT UPON EGGS. 119 sometimes find them quickened by this very exposure into their larva or grub state*." It woiild have been well if some more accurate authority liad been given for so miraculous a fact than this general statement ; the appearance of mag-g-ots on broiled meat, from which the inference is apparently made, seems rather to indicate that eggs, or more probably ovo-viviparous larvse, had been deposited there, not before^ but after the broiling. One certain result of all such experiments is, that eggs are more capable of withstanding heat than the animals producing them; and from similar experi- ments the same law appears to hold with the seeds of plants, which also withstand more heat than eggs. Water increases the destructive influence of heat. The causes upon which these curious facts depend do not appear to be well understood. It is certain, however, that the life of an animal in the G^om each other, found the longest to be those only in which the grubs were hatched in my presence. If I removed them from the workers, before they attained their full length and transparency, they dried up, and the grubs never quitted them." Huber is inclined to attribute this remarkable in- crease and transparency to the humidity imparted to them by the vvorking ants who so assiduously pass them through their mouths. "For," he adds, "if they be not surrounded with a liquid, or preserved from the influence of the external air, their pellicle, moistened every instant by the workers, may preserve a certain degree of suppleness and expansibility, according to the development of the included grub §.'' The most minute observations, however, of this khid, which have hitherto been pubhshed, were made * Reaumur, Mem. vol. iil. p. 479. tRtisel, Insecten. vol. iii. p. 152, % Dc Geer, Mem. des Insectes, vol. vii. p. 145. §M. P. Huber on Ants, p. 72. DEVELOPMENT OF EGGS. 123 by Heroldt on the eggs of the garden-spider {Epeira diadema), to which we formerly alluded. He divides the process of hatching into twelve periods, according* to the progress of development. This progress is not measured by time, as has been done in experimenting on the eggs of birds. The germ, or cicatricula, which is composed of minute granules, when placed in a due temperature, begins to expand towards the extre- mity of the egg, till it takes the form of a comet, whose nucleus is the centre of the germ, and whose tail consists of transparent globules. On continuing to expand, or rather to disperse its granules, they appear to be decomposed into imperceptible molecules, producing a sort of translucent cloud, through which the globules of the yolk may be distinguished. The place which the germ previously occupied appears as a single transparent point. The cloudy matter next accumulates round the centre of the germ, assumes a pearly aspect, and becomes solid and opaque. This is the rudiment of the embryo spider, tiie outline of whose head and body becomes appa- rent, occupying a little more than a fourth of the egg. At first this embryo appears homogenous, but by and bye four little archlets are seen, which are the rudi- ments of the legs, and at the same time the outlines of the mandibles are formed. The whole seems to derive nourishment from the yolk, in which it is rooted as a parasite plant upon a tree. When the embryo spider is near its exclusion, it completely fills the inte- rior of the egg^ the shell of which moulds itself closely around the body, and it looks like the nymph of a beetle*. When sufficiently developed, it makes a rent in the shell, as was first observed by De Geer, oppo- site the breast, through which it pushes its head, and successively disengages its body ; but the shell still envelopes the legs and feet, and it is not without a * Hcroldtj Kxercit. de Gener. Aranearuin in Ovo. 124 INSECT TRANSFORMATIONS. n-reat deal of trouble, by alternately stretching' out and contracting them, that it succeeds in rending this, and sets itself at liberty*. Even then the young spider can neither spin a web nor catch prey ; for it is still enveloped in an extremely delicate membrane, which it does not moult unless the weather is favourable and fine f . Hatching of the egg of (he garden-spider {Epeira dtadema'). a, natural size, b, egg magnitied, the cicatricula (a white spot) in the front. C, the germ enlarged ; a, the head, and b, the body of the embryo, d, the embryo spider ready to cast off its first skin. The latter circumstance will enable us to explain some experiments made by Redi, who kept spiders newly hatched for many months without food|. In the experiments made by us upon the eggs of the wolf- spider (JLycosa saccata), we more than once kept the young in boxes, where they were forgotten and without food ; and we uniformly found that they re- mained lively and well so long as they did not cast their embryo skin ; but when they did moult, they could not long survive the want of sustenance §. In the eggs of moths, the embryo, previous to ex elusion, may be seen through the shell, snugly coi ed * De Geer, Mem. vii. p. 196. i f Diet. Classique d'Hist. Nat. xii. 141. I X Redi, Esperienze, 99. ^ J. R. j CONSTRUCTION OF EGGS. 25 up in a ring, as is distinctly shown in many of the beautiful and accurate figures of Sepp *. a, egg of the privet hawk-moth (^Sphin.v lAgustri) magnified, showing Jhe inclosed embryo, b, the caterpillar when grown. In the case of the eggs of birds, the chick, when fully developed, breaks the shell with its bill, the point of which is then furnished with a hard scale. This is evidently contrived by providential wisdom for this very purpose, for it drops off in a few days after the chick is excluded. It is probable that the larvae of many insects which are furnished with strong man- dibles gnaw their way through the egg-shell ; but we know that there are others which, like the spider, rupture their envelope, since the edges appear ragged and irregular. Others, again, seem to have an open- ing provided for them, in a door, which only requires them to push it open. This is the case with the louse {Pediculus humanus), and with the bird-louse {Nirmus), found on the neck feathers of the golden pheasant. A still more ingenious contrivance was discovered by the Rev. R. Sheppard, in the egg of a field-bug {Pentatoma, Latr.), which is not onlyfur- * Der Woiidercn Gods, passim. 126 INSECT TRANSFORMATIONS. Doors in egofs for the escape of the larvae, a, egg of the louse {Pediculus hurnanus). b, egg of the penta- toma. c, shell of a moth's egg found upon the dew-berry — all mag- nified. nished with a convex lid, but with a lever of a horny texture, and in the form of a cross-bow, for opening it, the handle being fixed to the lower part of the egg- by a membrane, and the bow part to the lid*. On the leaf of a dew-berry (^Rubus ccesius) we found a beautifully ribbed egg of some moth, which, having been brought into our study, in January, 1830, was hatched by the warmth, and exhibited an opening similar to the elastic cocoon of the emperor-moth ; each of the ribs having expanded to allow of the escape of the caterpillar. The period at which the eggs of insects are hatched after deposition depends mainly upon temperature; for by keeping them in an ice-house in summer, the hatching maybe retarded t, as it may be hastened (witness the instance in the preceding paragraph) by heat in winter; but there are many other circum- stances unknown to us which often hasten or retard the process. The eggs of the blow-fly {Muscavomi- torid) are said to hatch within two hours |, while those of several moths, and numerous other insects, remain unhatched for six or nine months ; perhaps, in some cases, even for one or more years. It is worthy of re- * Kirby and Spencc, iii. 104. f Reaumur, Mem. t Nouv. Diet. d'Hist. Nat. xii. 564. PERIODS OF HATCHING. 127 mark, however, that, the periods of hatching corre- sjDond ill a striking- manner with the leafing of trees, and the appearance of other materials fitted for the food of the young-. We observed a good example of this in the spring of 1829. A lackey-moth had deposited during autumn a spiral ring of her eggs on the branch of a sweet-briar planted in a garden-pot out of doors. We removed this into our study during- the winter. Here the warmth caused the tree to bud, and at the same time hatched the lackeys about a month sooner than those out of doors. Owing to the same cause, se- veral colonies of the caterpillars of the brown-tail moth revived from their torpidity, and came forth from their winter nests before the hawthorns were in leaf, a cir- cumstance which would not have happened to them out of doors*. Kirby and Spence give an instance precisely similar, of the eggs of an aphis found on the birch, and hatched in-doors a full month before those in the open airf. It is a remarkable circumstance, long observed by collectors, that the male broods of insects appear earlier than the female broods ; and it would appear from the following fact, that there is a similar retarda- tion in the hatching of female eggs. "Upon the leaf of a poplar tree were found three eggs of the puss- moth {Centra rinula), two of which were hatched about two weeks before the other. The first were males, the last a female. As they were on the same leaf, and presumed, therefore, to have been laid by the same parent, at the same time, the differ- ence of hatching could not have arisen from difference of weather, exposure, &c. I" In the case of the lackeys on the sweet-briar above mentioned, some were hatched several days before others, but whether these were of ditferent sexes we did not ascertain. * J. R. f Kirby and Spence, bitr. ii. 434. X J. Rcnnie,in Mag. of Nat, Hist. vol. i. p. 373. 128 SECTION IL— LARViE* Chapter VI. Structure of Caterpillars, Grubs, and Maggots, It is reported by Boerhaave, in his life of Swamrp^r- dam, that when the Grand Duke of Tuscany was visiting the curiosities of Holland, in 1668, he found nothing more worthy of his admiration than the na- turalist's account of the structure of caterpillars, — for Swammerdani, by the skilful management of instru- ments of wonderful delicacy and fineness, showed the prince in what manner the future butterfly lies neatly folded up in the caterpillar, like a flower in the unexpanded bud. He was, indeed, so struck with tliis and other wonders of the insect world, dis- closed to him by the great naturalist, that he made him a princely otTer to induce him to reside at his court; but Swammerdam, from feelings of indepen- dence, modestly declined to accept it, preferring to continue his delightful studies at home, 'i'he facts which thus struck the Duke with admiration we shall now endeavour, with the aid of Swammerdam, to trace. But, before we proceed, it may not be out of place to advert to some very novel views which have * It may be proper to repeat here, that an insect when hatched from the egg, is called by naturalists larva ; and in popular lan- guage, ^.cattrpiUar, or grub, if furnished with feet, and Amaggotf wonn, or (pintle, ii without feet. ANIMAL AND VEGETABLE TRANSMUTATIONS. 129 been recently started by continental naturalists, who maintain that vegetables are actually converted into animals, and these ag-ain into vegetables. It must be obvious, we think, from the details we have already given, that the doctrine of transmuta- tion^ so far as regards insects, is equally absurd and impossible with the pretended alchemical transmutation of lead and other inferior metals into gold and silver ; which doctrine was, indeed, supported upon the sup- posed fact of insects being thus transmuted *. But vi- sionary as either of these may appear, they have both been supported by men of talent and distinguished reputation. It does not, perhaps, at first sight seem more impossible, that water should be transmuted into diamonds, or brass into gold, than thutan egg should disclose a chick or a caterpillar, or that a caterpillar should change into a butterfly or a beetle ; but by adhering rigidly to facts, and rejecting as rigidly all fancies and analogies, how plausible soever they may appear, we are certain that the latter changes are of common occurrence, whereas the former are contrary to all experience, and to the best experiments. We say the 6e.s^ ; because observations, if not experiments, have been made for the express purpose of proving such improbable transmutations. '* I have shown to a great number of persons," says Professor Agardh, "the changeable crow silk {Conferva mutahilis. Roth ; Draparjialdia in. BoRY St. V.) in its state of a plant, the 3d of August, change by the 5th into molecules endowed with loco- mobility, reunite by the 6th into simple articulations, and reconstituted by the 10th into the primitive form of the plant t-" Previous to this (in 1814) Professor Nees von Esenbeck, of Bonn, published similar obiser- * Sir Theodore Mayerne, Epist. Dedicat ad Theatrum Insect. MouffetU. f Agardh, Diss, de Melamorph. Al^arum. 1820 130 INSECT TRANSFORMATIONS. vations, in which he remarks, that '* as the phenomena in question appear to contradict certain principles admitted into the reigning systems, we often prefer rather to deny the conclusions of candid and ex- perienced observers than to receive what has hitherto been regarded as untenable by generally admitted au- thority. In this situation are placet! all observations upon the transition or metamorphosis of vegetable life (characterized by immobility) into animal life (cha- racterized by mobility) ; — the moment when a being, arrived at the period of its existence, continues itself, as it were, by a new creation, and the animated em- bryo developes itself into a motionless vegetable*." Agardh, in his account of another allied family {Ocillatorice), has even given figures, first of the plant, and then of the animalcules into which its filaments are converted f, which induced Bory St. Vincent to remark sarcastically, that '* all nature appears, to the Professor of Lund, to be nothing but confervse travestied. |'' Passing over what has been published on this strange doctrine by Vaucher, Girod-Chantrans, Treviranus, Cams, and others, we shall only stop to mention the more recent observations of Francis Unger. The plant he selected was the Conferva dilatata /3 of Roth. *' Within the space of one hour," says he, " I succeeded in tracing, not only the dimi- nution of vitality and death of the animalcules, but also the subsequent development of the dead animals into germinating plants, in such a manner as to establish the truth of the fact." He adds with great simplicity, " I could scarcely believe my own eyes §." Like Agardh, he has given figures of these miracu- * Quoted in ' Annales des Sciences Naturelles' for 1828. f Agardh, Icones A)g. ined. i. 10. I Diet. Classique d'Hist. Nat., x. 469. ^ Annales des Sciences Nat , 1828. ANIMAL AND VEGETABLE TRANSMUTATIONS. 13! lous changes, which our readers may be curious to see. Supposed animal and vegetable metamorphoses. Since the only proof of these plants being trans- muted (as is alleg-ed) into animals, appears to be their acquiring motion*, and, as linger says, " swimming freely about ;'' we think we should be equally entitled to infer that camphor is animated because it moves spontaneously when thrown into water. This property in camphor has not hitherto been satisfactorily explained ; and it would undoubt- edly be better to leave the phenomena described by our advocates for transmutation likewise unexplained, than to leap at once to their startling conclusions. " We might as well," says Bory St. Vincent, *' astonish the world with the discovery of a fig- tree transmuted into a mulherry-tree, because the Broussonetia, when young, has the leaves of the one, and when old of the other ; and by such a system of observing we shall end in looking upon the oak and the mistletoe as the same plant : the wand of Circe could not produce more astounding consequences * Nees von Esenbeck. 132 INSECT TRANSFORMATIONS. than the microscope does in the hands of such observers*." It is apparently a branch of the same untenable theory which maintains that the fluid termed by Heroldt the hlood of caterpillars is the only original portion of them, which, being endowed with a forma- tive power t, pro(hices an envelope for itself of mucous net-work (rete mucosu7ii), and this again, by means of a similar power, is successively transmuted into the caterpillar, the pupa, and the perfect insect J ; in some similar way, we suppose, to the formative power dis- played by water, when, during frost, it shoots into crystals of ice. But the framers of such theories seem to forget that living blood is a very different thing from inanimate water, and the growth and nutrition of animals from the chemical formation of crystals. Kirby and Spence very justly remark, that Heroldt's formative power is only an apology for ignorance, and that his denying the existence of what he cannot trace, is no proof of his doctrine, but of his mistake in sup- posing the first appearance of the organs of the but- terfly in his microscope to be literally their first existence. To suppose the blood, we may also remark, endowed with the power of creating insects, gets rid of no difficulty and explains no phenomenon, while it is altogether a gratuitous assumption, unproved and improbable. " Admirable discovery," exclaims Virey ; "as if you should affirm that a stone falls because it falls § !" We think it is St. Pierre who remarks, that Nature seldom permits philosophers to peep to the bottom of her basket ; and we have already * Dict.Class.d'Hist. Nat. X. 468. t The German term is " Bildende Kraft," i. e. Fis format rix, or Nisus formal ivus. I Heroldt, quoted by Kirby and Spence, iii. 83. § Quoted by Kirby and Spence. EMBRYO BUTTERFLIES. 133 recorded many instances, besides the one under con- sideration, of their strange mistakes in o-uessing at what they cannot fathom. We prefer followino- Swammerdam, Rtjaumnr, and Bonnet, in recording- what can be actually seen on examining the structure of caterpillars. In a chapter of Swammerdam 's Book of Nature, quaintly headed "An animal in an animal, or the butterfly hidden in the caterpillar," we find the fol- lowing details respecting the caterpillar of the large cabbage-butterfly {Pontia brassicce). The egg of this insect is of a yellow colour, flask-shaped, and marked with fifteen ribs, converging towards the smaller end, and extending a little beyond it. The Egg of the large cabbage-bntterfty (Pontia hrarM: