\ THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID THE LIBRARY OF ENTERTAINING KNOWLEDGE. INSECT TRANSFORMATIONS. BOSTON : LILLY & WAIT, (late WELLS # LILLY,) .tfG.tf H. Carvill, and E. Bliss, New-York; Carey ^ Hart, Philadel- phia ; W. 4- J. Neal, and E. J. Coale, Baltimore ; P. Thompson $ Ho- mans, Washington ; R. Cruikshank, Georgetown 5 W. M. Morrison, Alexandria; R. D. Sanxay, Richmond; C. P. M'Kennie, Charlottes- ville ; W. H. Berrett, Charleston, S. C.; Salmon Hall, Newbern, N.C. ; Mary Carroll, New-Orleans ; Odiorne & Smith, Mobile ; .7. P. Ayres Nashville, T. ; N. 4- G Guilford, Cincinnati ; Little $ Cummings, Al- bany; H. Howe, New Haven; H. ^ F. J. Huntington, Hartford; S. But- ler & Son, Northampton ; Whipple $ Lawrence, Salem ; Eli French, Dover; H. S, Favor, Eastport; and S. Colman, Portland. 1831. CONTENTS. / i v> ^ i - SECTION I. EGGS OF INSECTS, CHAPTER I. INTRODUCTORY. Page All insects come from eggs, 1 Curious experiment of Kircher, 2 Virgil's receipt for making a swarrn of bees, Origin of these ancient errors, 4 Bees in Sampson's lion accounted for, 7 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 afloat 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 The f worm i' the, bud' traced to its egg, 20 Insectiferous winds, 22 Supposed shower 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, 46 Number of irisect eggs, and their fecundity, compared with other animals, 46 CHAPTER III. Maternal care of insects respecting their eggs, 49 Instanced in a carpenter bee (Chelostoma), 50 Ichneumons compared to the cuckoo, 52 Proceedings of a solitary bee (Halictus), 53 Stratagems of a solitary wasp (Cereem)j 54 M368511 iv CONTENTS. Ovipositor of an ichneumon (Pimpla), 56 Experiments of Reaumur, 57 Common mistakes of Naturalists, 59 Parasite of the cabbage caterpillar (Pontia)> Egg parasites, Parasites of the aphides, Singular parasite of the cock-roach, Rare parasites of bees and wasps, 67 Tact of insects in discovering food for their young, 68 Sometimes select exotic plants, 69 Instanced in a leaf-miner (Tephritis?), 70 Solitary and gregarious caterpillars, 71 Life-boat of eggs constructed by the gnat, 72 Experiments upon it, Infallibility of instinct questioned, 76 Mistakes of instinct, 77 CHAPTER IV. Hybernation of insects' eggs, 79 Proceedings of the gypsey moth compared to the eider duck, ib. Singular groups of eggs, 81 Protection of eggs from heat, 83 Anal tweezers of moths, 84 Eggs in spiral groups, 85 Arched form of the lackey moth's eggs, 86 Hybernation of the eggs of aphides, 87 Singular protection of the eggs of cocci, 88 Coccus of the hawthorn, 90 Shell-formed coccus of the currant, 92 Hybernation of spiders' eggs, 93 Curious spider's nests, 94 Eggs of the vapourer moth on its cocoon, 95 Effects of (fold on insects' eggs, 96 Observations of John Hunter, 98 Insects not killed by severe frosts, ib. CHAPTER V. Hatching of insect eggs, 100 Structure of the eggs of birds, ib. Insects do not hatch their eggs, 101 Anomalous instance of the earwig, 102 Earwigs cannot get into the brain, 103 Partial hatching by spiders, 104 Experiments upon the wolf spider by Swammerdam and Bonnet, 105 Eggs hatched before they are laid, 108 Ovo-viviparous insects, 509 Coil of larvae in the body of a blow-fly, 110 Aphides sometimes produce eggs, sometimes young, 112 CONTENTS. V Page Care taken of these eggs by ants, 113 Cocco-viviparous flies (Hippoboscidaz), 116 Effects of heat upon eggs, 118 Management of silk-worms' eggs, 120 Effects of light on eggs, ib. Some insect eggs increase in size, 121 Growth of the eggs of ants, Developement of the eggs of spiders, Spiders live long without food, 124 Insects probably gnaw through their egg-shells, 125 Valves of insect eggs, 126 Period of hatching influenced by temperature, 127 SECTION II. LARVAE. CHAPTER VI. Structure of caterpillars, grubs, and maggots, 128 Meanings of these terms, Note, ib. Supposed transmutation of plants into animals, 129 Observations of Unger upon this, 130 Remarks of Bory St Vincent, 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 Difference of plants from insects, 137 Internal structure of caterpillars, 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, 146 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 (Nais) may be mistaken for larvae, 159 Syringe for respiration in a water larva, 161 Curious mask of the same larva, 163 Dust mask of the wolf bug (Reduvius), 165 CHAPTER VII. Growth, moulting, strength, defence, and hybernation of larvae, 166 Progressive increase 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 to renal gravel, Position of the hairs. in moulting, 173 VOL. VI. B VI CONTENTS. Page Casting of the interior lining of the stomach, &r, 174 Moulting of birds, 176 Cast skins sometimes devoured, 177 Mis-statement of Goldsmith, ib. Contrivances for escape from confinement, 178 Muscular strength ofinsects, 179 Fleas made to draw miniature coaches, 180 Numerous muscles of the cossus, Its wonderful strength, 184 Mis-statements respecting the strength ofinsects, 185 Means of escape by spinning, 186 Defensive hairs and spines of caterpillars, 187 Excrementitious covering of some larvae, 190 Origin of the froth on plants called cuckoo-spify 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'wonn in thirty days, 197 Remarkable change in the capacity of the stomach, 198 Instances of human voracity, 201 Jaws or mandibles of larvsR, 202 Caterpillars, ib. Blight caused by an oak-leaf-roller, 203 Ravages of the buff-tip, 204 Encamping caterpillars of the ermine moths, 205 Experiments with these, 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 JEgerise on currant and poplar trees, 220 Destruction of grain by Euplocami and Tinse, 221 Bee-hives injured by Gallarise, 222 Caterpillar which feeds on chocolate, 224 CHAPTER IX. Voracity of grubs, 225 Grub of the cockchafer or maj-bug, 226 Account of its transformation, &c, 227 CONTENTS. Vll Page Methods of destroying, Wire worm the grub of Hemirhipus, Probable mistake respecting the destruction of wheat, 231 Pea beetle of North America, 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, Extraordinary case of Mary Riordan, by Dr Pickells, 239 Authenticity of this case proved, 241 Fruit grubs, 242 N ut weevil and its transformations, ib. Apple-bud weevil, . 243 Voracity of Calosoma, 244 Rayed galleries of a bark-grub, 245 Ravages of locusts, 246 Their swarms in Southern Africa, 247 The Italian locust, 249 Migrations in Palestine and Europe, 250 CHAPTER X. Voracity of maggots, 252 Maggots of crane flies popularly called the grub, ib. Remarkable ovipositor, 253 Destruction of herbage on Blackheath, 254 Similar devastations in Poitou and Holderness, 255 Wheat fly, described by Mr Shireff, 256 Additional particulars by Mr Gorrie, 259 Observations ofKirby, 260 Mistake of Mr Markwick, 261 Hessian fly, as described by Mr Say, 262 Cheese-hopper the maggot of Piophila, 263 Wonderful structure of this maggot, 264 Its transformation into a fly, 265 Origin of the house fly (Musca domestica), 266 Mistakes of Ray and Reaumur, 267 Voracity of the maggots of blow-flies, 268 Instance of man devoured by them, \\ 3t Popular mistake respecting lady-birds, ggg Thair transformations traced to the egg, 270 Aphides checked by these and by Syrphidae, SECTION III. PUP^E. CHAPTER XI. Mechanism of suspending chrysalides, 272 Proceedings of larvae upon their approaching change, 273 In what manner some caterpillars suspend themselves, 274 Viii CONTENTS. Page Their attempts sometimes unsuccessful, Organ for holding fast, Suspensory cincture of other caterpillars, 279 Method of forming- this by the swallow-tail, "281 Parchment-like pupa case of flies (Muscidce), Flask-shaped pupae of Syrphidae, 284 Transformations of a Tipulidan gnat, 285 Mode by which the nymph is suspended, 286 Hooked aquatic pupa (Hydrocampa?)^ 287 CHAPTER XII. Form and structure of pupae, 288 The term of Metamorphosis objected to, ib. Harvey's fancies about transmutation, 289 Similar fancies of Goedart exposed by Swammerdam, 290 Structure of the pupa of the chameleon fly, 292 Pupa of the lappit moth, 293 Chrysalis and transformations of the peacock butterfty, 294 Origin of philosophic errors, 296 Changes produced on pupae by evaporation, 297 Objections to the theory of evaporation, 298 Respiratory organs of pupa?, 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 XIII. Transformation of pupae into perfect insects, 307 Theory of transpiration by means of heat, ib. Objections to this theory, 308 Experiments by Reaumur, 309 Chrysalides hatched under a hen, 310 Forcing of butterflies in winter, 311 Retarding the evolution of butterflies by cold, 312 Experiments on pupae led to the varnishing of eggs, ib. Illustrations of torpidity in animals and plants, 313 Various periods of disclosure in the same brood, 314 Supposed final cause of this, 315 Fixed time of the day for some insects to be evolved, 316 Remarkable evolution of the gnat, 317 Still more remarkable instance of the blood-worm, 319 Netted doors in the pupa cases of caddis-flies, 320 Bellows-apparatus in the pupa of the blow-fly, 321 Contrivance in the pupae of wood feeders, 322 Singularity in the locust moth, 323 Ingenious contrivance in a small leaf roller, 324 CONTENTS. IX Page Mistake of Bonnet with respect to the teazle-moth, 325 Pupa cases opened by extraneous assistance, 328 Observations on this by the younger Huber, 327 Experiment by Dr J. R. Johnson, 329 De Geer's observations contrary to those of Svvara- merdam, 330 Remarkable circumstance in the hive bee, 331 SECTION IV. PERFECT INSECTS. CHAPTER XIV. Expansion of the body and wings in insects newly trans- formed, 333 Structure of birds to contain air, ib. Expansion in the fly of the ant-lion, 334 The mandibles prove it carnivorous, 335 Transformations of dragon-flies, 336 Folded wings of some two winged flies, 338 Malpighrs 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 butterfly, 342 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 Theories devised to account for crimson-snow, 352 Curious fact explaining this, by Mr T. Nicholson, 354 Does not explain the red snow of the Alps, 355 CHAPTER XV. Peculiar motions of insects, 356 Motion indispensable to life, ib. Anecdote of a water-measurer, 357 Mode of combing themselves used by spiders, 358 Oscillatory motions of some tipulidae, 359 Vibratory motions of syrphi on the wing, 360 Similar motions of hawks, red-breast, &c, 361 Experiment on Scioptera vibrans^ 362 Illustrated by the wag-tail, &c, 363 Gnat dances in winter, ib. Opinion of Wordsworth and others, 364 Similar aerial dances of rooks, ib. Night-gambols of Corethrce ? on a book, 365 Circular movements of a summer fly, 366 Sportive movements not necessarily social, 367 Account of the whirlwig, by Kirby and by Knapp, ^ 36& VOL. VI. B* X CONTENTS. Page Remarkable structure of its eyes, Battles of butterflies, Choral assemblies of ephemeridae, 273 Account of these by Reaumur, ib. Sports of ants, 376 GjTnnastics of ants, according to Huber, 377 CHAPTER XVI. Peculiar locomotions of insects, Examples from quadrupeds, ib. Singular movements of some plant-bugs, 380 Sailing of the whirlwig beetle, Walking on water by spiders, &c, Walking through water by aquatic mites, Oblique pace of midges, Insect with its legs on its back, Rapid galloping of the strawberry mite, 386 Slow movements of the oil-beetles, Supposed sponges in the foot of the fly, 388 Correct notions of Derham and White, proved by Sir E. Home, Apparatus in the feet of flies, Leaping muscles of the flea, Leaping of grasshoppers and Springtails, Springing of spiders on their prey, 394 Flight of insects, 395 Mechanism of insects' wings and their muscles, ac- cording to M. Chabrier, 396 Flying of spiders without wings, 397 CHAPTER XVII. Rest of insects, 399 .Night insects rest in the day, ib. Day movements of other insects, 400 Insects have no brain nor spinal cord, ib. Want also a proper heart as well as blood, 401 Supposed pulse in insects, ib. No circulation, 402 Alleged discovery of an insect circulation, by Dr Carus, ib. How the circulation is affected in the sleep of man, 404 The same effects cannot take place in insects, 405 Sleep of senses not equally profound, 406 Torpidity of insects in winter, ib. Hybernation of ants, 407 Anecdotes from Huber, 408 Hibernation of bees, 410 Discrepancies of opinion among naturalists 413 Hybernation of the hearth cricket, 414 ILLUSTRATIONS. Page 1. Comparative figures of a bee and a syrphus, 4 2. Cell of a queen of the Termites bellicosi, broken open in front; the labourers surrounding the queen, and carrying off the eggs, 15 3. Groups of eggs of the rose-leaf roller on a pane of glass, 20 4. Plants of sphcerobulus, natural size, 26 5. Ditto, magnified view, ib. 6. Ditto, sectional view, with the seed just previous to projection, ib 7. Ditto, with the seed in the act of projection, ib. 8. Ditto, immediately after projection, ib. 9. Microscopic views of applo and pear mould, 30 10. Eggs of a butterfly and of a moth, magnified, 41 11. Magnified egg of the angle-shades moth, 42 12. Sea egg, natural size, ib. 13. Rgg of the meadow brown butterfly, magnified, 43 14. Egg of the brimstone moth, magnified, ib. 15. Dung-fly, with its eggs magnified, and mode of depo- sition, 44 16. Lace-winged fly, and position of its eggs on a twig of lilac, 45 17. Ichneumon fly, with its ovipositor, magnified, 57 18. Ichneumon flies ovipositing, 58 19. Generation of ichneumons, seven figures, 62 20. Magnified view of a parasite fly (Evania apendi- g aster) , 66 21. Bee parasite (Stylops Melitta}, 67 22. Leaf-mining maggots and fly, four figures, 70 23. Gnats forming their egg-boats, 74 Xli ILLUSTRATIONS. Page 24. Magnified view of the boat of gnats' eggs, 75 25. Female gypsey moths, and modes of depositing their eggs, four figures, 81 26. Females of the brown and gold-tailed moths, two figures, 83 27. Tweezers of the brown and gold-tailed moths, mag- nified, two figures, 84 28. Spiral groups of eggs of an unknown moth, 85 29. Eggs of the lackey moth wound spirally round a twig of hawthorn, natural size and magnified, two figures, 86 30. Eggs of the coccus, covered with down, and with the bodies of the mothers, 89 31. Magnified cochenille insects, male and female, two figures, ib. 32. Eggs of the hawthorn coccus, covered by the body of the dead mother, 91 33. Ditto, one of these magnified, ib. 34. Section of ditto, showing the eggs within, ib. 35. Suspended spiders' nests, three figures, 94 36. Vapourer moth, male and female, and deposition of eggs, three figures, 95 37. Drum of the ear, showing that there is no passage through it to the brain, 103 38. Chequered blow fly, 1 10 39. Abdomen of ditto, opened and magnified, showing the coil of young larvae, ib. 40. Coil of larvae of ditto, partly unwound, ib. 41. Large gray blow-fly, with the abdomen opened, show- ing the young maggots, 111 42. Breathing apparatus of the maggot of a large gray blow-fly, ib. 43. Spider flies, two figures > 117 44. Generation of a water-mite, four figures, 121 45. Hatching of the egg of the garden spider, four figures, 1 24 46. Egg of the privet hawk moth, magnified, showing the inclosed embryo, 125 47. Caterpillar of ditto, when grown, ib. 48. Construction of eggs to facilitate the escape of the larvas, three figures, 126 49. Supposed animal and vegetable metamorphoses, 131 50. Egg of the large cabbage butterfly, 133 5 i . Embryo butterflies as they appear in the bodies of ca- terpillars, two figures, 135 52. Female of the perfect cabbage butterfly, ib. 53. Magnified view of a section of the bud of a laburnum, 1 36 ILLUSTRATIONS. Xlli Page 54. Section of a bean-seed, 136 55. Seed-leaves, root, and first true leaf of the beech, ib. 56. Dissection of the water-grub of a May-fly, 139 57. Caterpillars of the Clifden nonpareil feeding on the gray poplar, 142 58. Ditto, in a more advanced stage of growth, 143 59. Walking-leaf insect magnified, 144 60. Transformations of the brimstone moth, 145 61. Caterpillars of the swallow-tailed moth, 146 62. A two-winged fly ( Volucella plumat a), 149 63. Transformations of the puss moth, 152 64. Lobster caterpillar, 153 65. Aquatic grubs of gnats in a glass vessel of water, 155 66. LarvsB of the common-gnat, floating in water, two figures, 156 67. Buoy-like structure in the tail of a water-grub of a two-winged fly, 157 68. Telescopic-tailed water-larvae, three figures, 158 69. Water-worms, two figures, 159 70. Grub of the dragon-fly, and various parts of its body magnified, five figures, 162 71. Mask of the dragon-fly grub, four figures, 164 72. Moulting of caterpillars, and magnified views of parts, ten figures, 172 73. Exuvia and pulmonary vessels of the rhinoceros beetle, 175 74. Goat moth caterpillar escaping from a drinking-glass , 178 75. Magnified view of the dorsal muscles of the upper half ofthecossus, 182 76. Caterpillar of cossus escaping from under a loaded glass, 184 77. Methods used by spiders and caterpillars for ascending their threads, 186 78. Caterpillar of the tiger-moth, two figures, 187 79. Grub of the museum beetle, natural size and magni- fied, two figures, ib. 80. Tail of ditto, magnified, ib. 81. Hairs of ditto, magnified, two figures, ib. 82. Thorny hairs of caterpillars, three figures, 189 83. Green tortoise beetle (Cassida equestris), 191 84. Grub of ditto, magnified, to show its anal forks, ib. 85. Grub of ditto, with its canopy of excrements, ib. 86. Spit frog-hopper, and froth covering the grub of the same, two figures, 192 87. Caterpillar of the drinker moth, two figures, 194 88. Caterpillar of the angle-shades moth, ib. XIV ILLUSTRATIONS. 89. Moth of ditto, 194 90. Viscera of the cossus, two figures, 91. Caterpillar of Vanessa urtica, magnified, 200 92. Intestines of ditto, ib. 93. Intestinal canals of the caterpillar, pupae, and butter- , fly, five figures, 94. Buft-tip caterpillar, and moth of ditto, two figures, 204 95. Encampment of the caterpillar of the small ermine on the Siberian crab, 96. Transformations of the gamma moth, five figures, 212 97. Saw-fly of the gooseberry, and caterpillars, four figures, 214 98. Caterpillar of the saw-fly (Nematus Caprea) on the osier, 217 99. Caterpillar of the saw-fly (Selandria alni) on the alder, ib. 100. Transformations of the grain moth, seven figures, 221 101. Transformations of the honeycomb moth, seven figures, 223 102. Transformations of the cockchafer, nine figures, 227 103. Wire-worm and click beetle, 230 104. Zabrus gibbus, 231 105. Melolontha ruficornis, ib. 106. Corn weevil, 234 107. Meal-worm, and the beetle produced from it, 235 108. Transformations of the tabby moth, six figures, 236 109. Intestinal worms, three figures, 239 110. Churchyard beetle, in the grub and perfect state, four figures, 241 111. Nut and apple-tree beetles, eight figures, 243 112. Bark mined in rays by beetle grubs, 245 113. Locust, 251 114. Ovipositor and eggs of the crane-fly, 253 115. Crane fly ovipositing, and the larva beneath in the earth feeding upon grass roots, 254 116. Germination of a grain of wheat, 259 117. Transformation of the wheat-fly, three figures, 260 118. The Hessian fly, 261 119. The Markwick fly, ib. 120. Transformations of the cheese-hopper, seven figures, 265 121. Transformations of Bibio hortulanus, six figures, 267 122. Transformations of the lady-bird, six figures, 270 123. Transformations of the lace-winged fly and syrphus, five figures, 271 124. Caterpillar of Vanessa Jlntiopa, three figures, 274 ILLUSTRATIONS. XV 125. Suspended caterpillar of Vanessa JLntiopa splitting its skin for the evolution of the chrysalis, four figures, 276 126. Chrysalides of Vanessa urticce suspended, with the anal hooks magnified, and old skin fallen off, four figures, 278 127. Black-veined white butterfly, caterpillar, and chry- salis, three figures, 280 128. Caterpillar and chrysalis of swallow-tailed butterfly, three figures, 281 129. Pupae of blow-fly and syrphus, four figures, 284 130. Transformations of the gnat (Corethra plumicor- ms), six figures, 287 131. Pupa of chameleon fly, three figures, 292 132. Pupa of lappit moth, three figures, 294 133. Chrysalis of Gonepteryx Rkamni, 300 134. Pupa of Laria fascelina, ib. 135. Pupa of Sphinx Ligustri, ib. 136. Spiracles of pupae, two figures, 302 137. Pupae of the gnat and Tipula , four figures, 304 138. Transformations of Chironomus plumosus, four figures, 305 139. Case fly, with the pupa, and the grate-works of the opening of the latter, four figures, 321 140. Pupas of Cossus and JEgeria, 323 141. The fly and pupa of the ant-lion, four figures, 335 142. Transformation of the dragon-fly, five figures, 337 143. Blow-fly, magnified, two figures, 338 144. Wings of insects, showing the nervures, six figures, 344 145. Twenty-plume moth, two figures, 345 146. White-plume moth, ib. 147. Specimens of deformed butterflies and moth, three figures, 350 148. Red spider, and the head, magnified, two figures, 359 149. Head of the garden spider magnified, ib. 150. Phalangium, 360 151. Hydrometra stagnorum, magnified, ib. 152. Ploiaria vagabunda, magnified, 381 153. Neides elegans, magnified, ib. 154. Hydrometra stagnorum, natural size, 382 155. Hydrachna geographica, magnified, two figures, ib. 156. Velia rivulorum, ib. 157. Julus terrestris, two figures, 386 158. Oil-beetle, ib. Xvi ILLUSTRATIONS. 159. Nycteribia Hermanni, 386 160. Feet of the fly, greatly magnified, four figures, 391 161. Flea, magnified, 392 162. Velvet spring-tail, magnified, 394 163. American spider (Mygale avicularia) destroying a bird, 395 164. Muscular ribbons for moving the wings in Syrphus inanis, magnified, two figures, 397 165. Syrphus, 398 INSECT TRANSFORMATIONS. SECTION I. EGGS OF INSECTS. CHAPTER I. All Insects come frdm Eggs as Plants do from Peeds. Vulgar errors of Insects being generated by Putrefaction and Blighting Winds disproved by experiment. IT was universally believed by the ancient philoso- phers, that n.aggots, 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 devour- ing, or a flock of sheep from the grass field in which they graze. Another opinion, perhaps still more gene- rally diffused, is that caterpillars, aphides, and other garden insects which destroy the leaves of plants, are generated, propagated, or, at least, spread about, by certain winds or states of the air, mysteriously and indefinitely termed blight. The latter belief is, pro- bably, not so easy of immediate refutation as the for- mer; 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 off fanciful opinions regarding them, since it is difficult for common observers to detect mistakes, VOL. vi. 1 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 : f Take some snakes,' says he, c of whatever kind you 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 that the piece of ground be exposed to the spring sun, and in eight days you will see the earth strewed 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, c 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 hand.|' 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. t Redi, Generat. Insectorum, edit, Amstel. 1686. GENERATION OF INSECTS. O tionably, that the imagination of Kircher had magni- fied 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, un- finished, 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, how- ever, they ' unfolded their wings, and changed into a vivid green, marvellously brilliant ' most proba- bly the green flesh-fly (Musca Ccesar. 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 after- wards 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 aquati- cus, LINN.), and between this and a young eel. This fabled transformation of hair, which we have heard maintained even by several persons of good educa- tion, 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 c Episode of Aristseus recovering his bees ' has been pronounced to be ' perhaps the finest piece of poetry in the world,' we must be permitted to say that it is quite fabulous and unphilosophical. The passage runs thus : Oft from putrid gore of cattle slain Bees have been bred. * * * A 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 4 His horns just bending in their second year; 4 INSECT TRANSFORMATIONS. Him, much reluctant, with o'erpow'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 battered 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 on high. Meanwhile the juices in the tender bones Heated ferment; and, wondrous to behold, Small animals, 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 tig-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 wings, and short antenna?, while all bees have four wings, and long antennae. Neither the flies nor the b Comparative figures of a bee (a) and a syrplms (b). 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 found in the carcasses of animals in summer, * somewhat resemble those produced by the eggs of bees. How- ever ridiculous,' he adds, c the opinion must appear, many great men have not been ashamed to adopt and defend it. The industrious Goedart has ventured to ascribe the origin of bees to certain dunghill worms,* and the learned De Mei joins with him in this opi- nion; though neither of them had any observation to ground their belief upon, but that of the external re- semblance between bees and certain kinds of flies (Syrphidce) produced from those worms. The mis- take of such authors should teach us,' he continues, * to use great caution in our determinations concern- ing things which we have not thoroughly examined, or at least to describe them with all the circum- stances observable in them. Therefore, although this opinion of bees issuing from the carcasses of some other animals by the power of putrefaction, or by a transposition 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 requisites 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 him- self out of that labyrinth of idle fancies and unsup- ported 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 re- sults of his experiments upon the flesh of snakes, for * The maggots of Eristalis tenax, FABR. E. apiformis, MEIGEN, and other Syrphida, well known in common sew- ers by their long tails, like those of rats. t Swammerd. Book of Nature, i, 228. VOL. VI. 1* 6 INSECT TRANSFORMATIONS. several species of flies were produced, giving some countenance to the opinion of Aristotle, Pliny, Mouf- fet, 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 of 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 or 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 any thing 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, I and other small animals which they cannot re- move. J These facts, which are unquestionable, may at first view appear to contradict the Scripture history * Aristotle, Hist. Animal, ix, 40. Pliny says, ' Ornnes car- ne vescuntur, contra quarn apes, quae nullum corpus aitingunt* t Huish on Bees, p. 100. i Insect Architecture, p. 109. GENERATION OF INSECTS. 7 of Sarnson, who, having killed a young lion in the vineyards of Timnath, * after a time turned aside to see the carcass of the lion: 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 stilt 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, c not only do not live 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 Spense seem disposed to consider Sam- son's bees, as we have done those of Virgil, to be flies resembling bees; but the ' honey' which Samson < took in his hands and went on eating,' is fatal to such an exposition. The ancients had. another fancy respecting the * Judges, xiv, 8. 8 INSECT TRANSFORMATIONS. propagation 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,! 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. 'J 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 egg) 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 4 Earth-born' (Erich- thonii), and wore golden tree-hoppers (Cicadai) in their hair, erroneously supposing these insects to have a common origin with themselves. Lucretius * Hist. Animal, v, 22. t Le Portrait de la Mouche a Miel. Liege, 1646. t 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 Cicadae do not deposit their eggs in the earth, but on trees, &c. See Insect Architecture, chap. vii. GENERATION OF INSECTS. 9 affirms, that even in his time, when the earth was sup- posed to be growing too old to be reproductive, c many animals were concreted out of mud by showers and sunshine.'* But the ancients, it would appear, had the shrewd- ness seldom to venture upon illustrations of their phi- losophical 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 certbriformis, PARKINSON.)! Darwin, again, taking the hint from Epicurus, dreams that an- imals arose from a single filament or threadlet of mat- ter, which, by its efforts to procure nourishment, lengthened out parts of its body into arms and other members. For example, after this filament had im- proved 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 in- to 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 different forms of the bills of birds, whether hooked, broad, or long, were, he says, gradu- ally acquired by the perpetual endeavours of the crea- tures to supply their wants. The long-legged water- * Multaque nunc etiam existunt animalia terris, Imbribus et calido soils concreta vapore. JDe Nat. Rer. v, 795. t Robinet, Consid. Philosophiques dela Gradation Naturelle zotcenia Rosarta, mentioned before, which rolls the leaf of the rose-tree, is one of this kind. It is well known as furnishing the common poetical comparison of ' a worm i' the bud.' Early in autumn the mother insect deposits an irregularly oval-patch of yellowish eggs, covered with a cement Two groups of eggs of the Ro!e-leaf roller (Lozotcsnia Rosa- na) on a pane of glass. * J. R. GENERATION OF INSECTS. 21 of the same colour, sometimes upon the branches of the rose-tree, but more frequently, as we have ob- served, upon some smooth object contiguous. For several successive seasons, we have found more than one group of these eggs upon the glass panes, as well as the frame work, of a window, beneath which a rose-tree has been trained. At present (January 1830) there are two of these groups on one pane, and three on the frame-work; and as each contains about fifty eggs, should they all be successfully hatch- ed, two or three hundred caterpillars would at once be let loose, and, streaming down simultaneously upon the rose-tree beneath, would soon devour the greater number of its buds. As the window faces the east, the sudden appearance of the insects would make it appear not unplausible that they had been swept hither by an easterly wind. We found, during the same winter, an extraordina- ry number of similar groups of the eggs of a leaf- roller (Lozolcenia Ribeana?) on the branches of the gooseberry and red-currant, in a garden at Lee. On some small trees, from two to ten groups of eggs were discovered; and as each group consisted of from thirty to fifty, a caterpillar might have been hatched for every bud. After the severity of the season was over, we had the piece of bark cut off on which these eggs were attached; and though they had been exposed on the bare branches to the intense frosts of 1 829-30, they were hatched in a few days after being brought into our study. As the currant- trees were not then come into leaf, we had no food to supply them with, and they refused the leaves of all other plants which we offered to them. Had they been permitted to remain on the trees till they were hatched, they would probably have not left a single leaf undevoured. For this spring, at least, these currant bushes will be safe from their attacks, and of 22 INSECT TRANSFORMATIONS. course will set at defiance the supposed blighting winds, which no doubt will, as usual, be accused of peopling the adjacent gardens with caterpillars. It may be well to remark, that these caterpillars, when hatched, are scarcely so thick as a thread of sewing silk, and being of a greenish colour, they are not read- ily found on the leaves, the opening buds of which they gnaw to the very core.* It does not seem to have ever occurred to those who thus speak of insectiferous winds, that they get rid of no difficulty by the supposition; for where, we may ask, is the east or any other wind to take up the insects or eggs which it is said to drift along? The equally sudden disappearance of insects all at once, which is also popularly attributed to winds, arises from their having arrived at maturity, and fulfilled the designs of Providence, by depositing their eggs for the ensuing season, when they all die, some in a few hours, though others survive for several days, but rarelv for weeks. The sudden and simultaneous appearance of great numbers of frogs, snails, and other land animals, has given rise to the extravagant opinion that they have fallen in a shower frcm the clouds; and some goodly theories have been devised to account for the pro- bable ascent of frog-spawn, and the eggs of snails, into the atmosphere by whirlwinds. The impossi- bility of this, in consequence of their specific gravity, is of course left out of consideration by the theorists. Our distinguished naturalist, Ray, when riding one afternoon in Berkshire, was much surprised at seeing an immense multitude of frogs crossing his path, and on looking into the adjacent fields he found that two or three acres of ground were nearly covered with them. They were all proceeding in the same direc- tion towards some woods and ditches; and he traced * J, egg of the biimstone-moth (Rumia Crata-gata), magnified. The design of the appendages to some sort of eggs is much more apparent, and affords us some admirable illustrations of prospective contrivance. The eggs of the ephemerae, for example, are smooth and oblong, resembling caraway comfits, a form which Swammerdam proved to be admirably adapted for diffusing them through the water, where, he says, they are dropt by the mother insect. For this pur- pose he placed ' a few of them on the point of a knife, and letting them fall gently into water, they immediately separated of themselves in a very curious manner.'* The same accurate observer describes a very remarkable appendage in the egg of the water, scorpion (Nepa cinerea, LINN.), an insect by no means rare in Britain. This egg is furnished with a coronet of seven bristles disposed like the down on the seed of the blessed thistle, ( Centaurea benedicta, WILLDENOW); and before they are de- posited these bristles closely embrace the egg next to them in the ovary like a sort of sheath, as if a chain of thistle-seeds were formed, by placing each successively in the bosom of the down of the one next to it. As the mother insect deposits these eggs in the stems of aquatic plants, the bristles, which are partly left on the outside, are probably intended to * Svvamm. Book of Nature, i, 104, 44 INSECT TRANSFORMATIONS. prevent the aperture from being closed up by the ra pid growth of the plant. Reaumur gives an interesting description of a similar egg deposited by a common dung-fly, of a yellowish-orange colour, (Scatophaga stercoraria, MEIGEN). These eggs are furnished at the upper end with two divergent pegs, which prevent them from sinking into the dung where they are placed by the parent, while they are permitted to enter suffi- ciently far to preserve them moist. Both circum- stances are indispensable to their hatching; for when Reaumur took them out of the dung, they shrivelled up in a few hours, and when he immersed them farther than the two pegs, they were suffocated, and could not afterwards be hatched.* , Dnng-fly Scatophaga Stercoraria) ; 6 r, front and side views of its eggs- magnified ; d d d, a number of these eggs deposited in cow dung. Before we began to study the habits of insects, we found upon a lilac-twig, in the neighbourhood of London, a singular production, which we took for a very delicate fungus, and supposing it not to be common, we carefully preserved the specimens; but we have since learned, with no little surprise, that these are the eggs of the lace-winged fly, (Chrysopa reticulata, LEACH.) Reaumur says that several naturalists have described them as fungi, which is not to be wondered at; for they consist of a small oval greenish-white head, similar to the apple-mould, * Rraumur, iv, 379. POSITION OF EGGS. 45 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 spi- der 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 near- ly of equal length. It is evidently the design of these footstalks to place the eggs out of the reach of the grubs of lady-birds (Coccinellce) arid of aphidivorous flies (Syrphi), which frequent the same situations and Twig of lilac, bearing the eggs of the lace winged fly (Ckrypscpa rtticulataj Leach). The fly is seen resting on the lowest leaf. 46 INSECT TRANSFORMATIONS. 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 de- posits eggs with a footstalk; and what is most singu- lar, these larvaB, 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 form- ed her cocoon that they devour her, and spin their own cocoons under its cover, j* The eggs of insects do not seem to hold any regu- lar 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 considerably lar- ger. 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 appears to hold to a certain extent amongst insects, the most prolific families belonging, with few exceptions, to those which devour vegeta- ble 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 (Libellulina, MAC LEAY), do not lay above two dozen eggs, the lace- winged flies (Hemerobidce) still fewer, and the noontide fly (Mesembrina meridiana, ME i GEN) only * J. R. t See Insect Architecture, pp. 195 325, 6. FECUNDITY OF INSECTS AND FISHES. 47 deposits two eggs; while a single plant-louse (Aphis), as we mentioned before from Reaumur, may be the living progenitor of 5,904,900,000 descendants, and the queen of the warrior white ants ( Termes bellico- susj SMEATHM.), 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. c Compared with the rest of ani- mated nature,' says Daly ell, c infusion animalcula are surely the most numerous: next are worms, insects, or fishes; amphibia and serpents, birds, quadrupeds; 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, in- ferior 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 egg at a time. How prodigious is the difference, 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 1 100. 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 as- carides. One naturalist found above 12,000 eggs in a lobster, and another above 21,000. An insect very similar to an ant (Mulillal) has produced 80,000 in a single day ; and Leeuwenhoeck seems to compute four millions in a crab. Many fishes, and those which in some countries seldom occur, produce in- 48 INSECT TRANSFORMATIONS. credible numbers of eggs. 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 spe- cies of sturgeon; 342,000 in a carp; 383,000 in a tench; 546,000 in a mackerel; 99:2,000 in a perch; and 1 ,357,000 in a flounder. But of all fishes hither- to 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, then, 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 extraordinary fecun- dity which, under favourable circumstances, produces countless swarms of insects that give origin to the opinion of their being spontaneously 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 egg 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 nume- rous. * Introd. Observ. to Spallanzani, xiv. CHAPTER III. Maternal Care of Insects in depositing their Eggs. Solitary Bees. Wasps. Ichneumons. Moths. Butterflies. Gnats. Mistakes of Instinct. LORD KAIMES, in his ' Gentleman Farmer,' men- tions the singular 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, therefore, has endowed female insects with the most wonderful acuteness and skill in anti- cipating the wants of their young, when they escape VOL. vi. 5 50 INSECT TRANSFORMATIONS. from the egg, and have no mother to direct or pro- vide for them. We have numerous beautiful instances of this in the solitary bees and wasps, which 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, (Chelostoma florisomne?) not so large as the domestic fly, and more slender in the body, instead of digging into the ground like its congeners,! 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 (Jlnobium pertinax) 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 gray 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 at 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 (Xylocopa), they were divi- ded by several partitions of the same membranous ma- terial. The circumstance, however, which induces us to give these details here, relates to the eggs deposited * See Insect Architecture, pp. 24 64, &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 stage of its exist- ence. 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 re- searches 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 surface, 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 stretch- ed its head when feeding to the centre, instead of eating at the circumference. The honey was also then become thicker in consistence, and, in conse- quence of what had been consumed, formed a hollow cup.* Reaumur describes the nest of a bee of the same family (Jlndrena 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 egg is placed above the surface of the fluid honey. | 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. 52 INSECT TRANSFORMATIONS. tering the young grub from the inclemencies of the weather, or from being preyed upon by birds. There are more insidious 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 Ichneumons, a name signifying PryerSj 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 manner would appear almost incredible to one who had not studied their economy; but it cannot fail to meet the young entomologist at the very * Phil. Trans, for 1788, p. 219. PRECAUTIONS OP INSECTS. 53 outset of his studies; for it is scarcely possible for many broods of insects to be reared without observing it. The insidious proceedings of these cuckoo insects, as we may not inappropriately call them, give rise to remarkable displays of ingenuity 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 female, 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 Chrysis or Tachina often glides into her domicil, and finds time to deposit its egg and to escape before her return. Other solitary bees exhibit both more civilization and more cunning; for the male assists, at 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 fulvocinctusy STEPH.), indigenous in the vicinity of London, has frequently fallen under our observation. It constructs a gallery, having on the outside only a single perpendicular passage, but bran- ching out into seven or eight, at the bottom of each of which is placed a globule of pollen kneaded up with honey about the size of a pea, where an egg is depos- ited. Walckeria'er, who observed these insects 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 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 otten seen, indeed, the ruby-tail fly (Chrysis VOL. vi. 5* 54 INSECT TRANSFORMATIONS. ignita), on approaching this vigilant sentinel, fly off in all haste, with evident fear of the consequences. But, as Walckenaer justly remarks, should the part- ner 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 from its post, and the forager enter without announcing its arrival, it is immediately driven back and pu- nished 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 ornatci), numbers of which make their nests in the very midst of their colonies. The wasps surround the interior margin of their holes with a rampart 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 poor 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- * Walck. Mem. des Abeilles Solit. 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 it, but not to kill 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 aurita, LATH., and C. quadrifasciata, Bosc) are of essential service to agriculturists by provisioning their nests with destructive weevils (Curculionidce), so injurious to orchards and nurseries.")" Other families of this order in a similar way provide for their progeny a supply of living insects of different species, of which interesting accounts have been given by more than one naturalist. J 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- * Walck. ; Latreille, Annales du Museum, torn, xiv; and Bosc, Ann. de 1'Agric, vol. liii. t Bosc, Ann. de 1'Agric., vol. liii. See Insect Architecture, pp. 26-33. $ Ibid, pp. 30 - 32. 56 INSECT TRANSFORMATIONS. dious intrusion of a common ichneumon fly (Pimpla manifestator, GRAVENHORST), easily known by its being black, with the legs red. This ichneumon sometimes 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 young one, closes up the doorway with a bar- ricade of kneaded clay. It is this very barricade 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 of those as the saw-flies or the tree-hoppers (Cicadce.) The ovipositor of all the true ichneumons (Ich- neumonidce) 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. manifestator) will be sufficient to give the reader a distinct notion of the others Being 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 perpendicular, a structure better fitted for acting upon clay, as the teeth will not become so readily clogged, and the instrument will be more easily retracted. The figures will make this more perspicuous than the best description. , the Pimpla manifcstator ; 6, its ovipositor opened outwards ; c c c e, magnified view of its ovipositor ; rf, the toothed point of the borer. In order to study the economy of the mason wasps (Odyneri) more effectually, Reaumur made an arti- ficial vespiary of sand and mortar upon a wall, which at the same time gave him an excellent opportunity of observing the manoeuvres of the ichneumons. * I perceived,' he tells us, 4 one of these ichneumons, at the instant it alighted on the spot under which so many of the little green caterpillars had been stored up by the wasps. Its long tail, which it carried horizontally, appeared to form but one 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 proportions 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 barricadoed 58 INSECT TRANSFORMATIONS. nest of the mason wasp. But although the insect appeared not to be disturbed by my observations, yet 1 was unable to perceive whether the toothed portion of the borer was pushed beyond the sides of the sheath. What I did see, however, convinced me that the in- strument 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. & 6, its ovipositor, c, an ichneumon, which has just bored through the closed substance of a sand wasp's nest at < , into which her ovi- positor, d, descends to the coil of caterpillars at/, where the egg is laid. t Reaumur, Mem. vi, p. 304. PARASITE EGGS. 59 Another parasite (Pimpla strobikllce, FABR.) is armed with a long ovipositor, with which it deposits its eggs 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 (Chalcididce, WEST WOOD). When the gall-fly ( Cynips) has deposited its eggs on the bud or the leaf of a plant in such a manner as to insure 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 or bedeguar of the rose.* The most obvious distinc- tion 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 fanciful notion of their being generated by a vegetative and sensitive soul in the plant itself, to which also he attri- buted the generation of the grubs found in nuts, cher- ries, and other fruits. ' There is nothing,' as Reau- mur justly remarks, c more fitted to humiliate the best reasoners, and to inspire them with a well-founded * See Insect Architecture, pp. 375 384. 60 INSECT TRANSFORMATIONS. distrust of novel opinions, than to see a man like Redi, who had declared open war against popular prejudices, and successfully combated many of them, thus adopt- ing a notion so improbable, or (to use a stronger term) so pitiable.'* It was Redi's countryman, Malpighi, who first discovered 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 bede- guaris, and Eurytoma stigma, STEPHENS) are para- sites, Redi had some cause for being puzzled to ex- plain the phenomena. 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, from 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 stopped short, and formed them into insects of a smaller size, and less "perfect struc- ture. f M. Goedart even persuaded himself, says Rc-aumur sarcastically, that he had observed the ca- terpillar 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 with the expected butterfly j was made up in their greater numbers ;J 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. 476. t Ray, Hist. Ins.,Pref. xv, and Cant. 137. j Goedart, quoted by R c aumur, vol. ii, p. 415. PARASITE INSECTS. 61 It must have occurred to the least attentive obser- vers of the very common cabbage caterpillar (Pontia Brassicce), 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 (Microgaster glomeratus, SPI- JNOLA), of a black colour, except the legs, which are yellow. By breeding these flies in a state of confine- ment, and introducing them to some cabbage caterpil- lars, their proceedings in depositing their eggs may be observed. We have more than once seen one of these little flies select a caterpillar, and perch upon its back, holding her ovipositor ready brandished to plunge be- tween the rings which she seems to prefer. When she has thus begun laying her eggs, she does not rea- dily take alarm; but, as Reaumur justly remarks, will permit an observer to approach her with a magnifying glass of a very short focus. 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 another cater- pillar 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 dis- agreeable. The eggs, it may be remarked, are thrust suffi- ciently deep to prevent their being thrown off when the caterpillar casts its skin; and, being in due time hatched, th4pgnibs feed in concert on the living body of the caterpillar. The most wonderful circum- VOL. vi. 6 62 INSECT TRANSFORMATIONS. stance, indeed, of the whole phenomenon, is the in- stinct with which the grubs are evidently guided 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 grown, they even eat their way through the skin of the caterpillar without killing it; though it generally dies in a few days with- out 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, the caterpillar a^^ontia Brassier. 6, the eggs of that butterfly glued to a leaf, c, Mid^Juster glomeratus, magnified, d d d, a magnified view of a dissected caterpillar, in whose body a number of ichneumon caterpillars have been hatched, e, silk co- coons spun by the ichneumons. /, grabs spinning cocoons. -, grub* 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 mo- thers contrive to deposit their eggs; for many of them are so very minute, as to find in the eggs themselves of larger insects a sufficient magazine of food 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 re- marked, 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 (Muscidce, LEACH), also, outbrave the danger of being caught and immolated by the mo- ther spider, and introduce their eggs either into or among those of their powerful enemy. These spiders' eggs are subsequently feasted upon by the progeny of the flies, a very natural reprisal for the ravages committed by this carnivorous race upon the whole generation of their fellows. That the mother flies ac- tually pierce the eggs of other insects was observed before the year 1730, by the accurate Vallisnieri, who says, ' I have seen with my own eyes a certain kind of wild flies deposit their eggs upon other eggs, and bore and pierce others with an ovipositor (aculeus), by means of which they have introduced the egg.'* Count Zinanni, another Italian naturalist, told Reau- mur, that, his attention being attracted by a small ichneumon fluttering about the eggs of butterflies, he soon observed it alight and fix upon one of these eggs ; and, without being incommoded by his ob- serving her proceedings through a strong magnifier, * Vallisnieri, Lettere, 80. 64 INSECT TRANSFORMATIONS. she bent her ovipositor, and plunged it into the egg. She performed the same operation upon many other eggs, which he carefully put under cover; and in about three weeks had from them a brood of flies of the same species with the one whose remarkable proceedings he had watched.* 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 (Platygaster ovulorum ? STEPHENS), which was produced from the caterpillars of the large white cabbage butterfly (Pontia 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 proceeds, c I found them rest- ing on large clusters of minute cocoons of an ovate form, the largest not exceeding two lines in length, and about the thickness of a caraway-seed. Each was en- veloped with a fine yellow silk, resembling that of the common silkworm (Bombyx Mori). On these clus- ters 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 had 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.'")" It is not a little interesting to remark, that this circum- stance corroborates the statement before given from * Reaumur, Mem. vol. vi, p. 297. t Loudon'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 upwards 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 (Micro gaster glomeratus ;) but, sup- posing them to be in the first instance egg 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 dlphidum, SPIN OLA), which plunges its eggs in their bodies; but the larvaB, when hatched, are by no , means safe, being liable to the attacks of ^bother fly of the same family (Gelis agilis, THUNBERG), as Dr Turton informs us.| * Bonnet, CEuvres, Svo, ii, 344. Kirby, referring to this passage, assigns, by mistake, only two to each egg. Introd. i, 342. t Transl. of Linn, iii, 48. VOL. VI. 6* 66 INSECT TRANSFORMATIONS. It is not common, however, for the ichneumon flies to deposit their eggs in the bodies of perfect insects, as in most cases they prefer the eggs, larvae, or pupae; but instances are on record of their grubs having been found in the former. The troublesome cock-roach (Blatta) is selected by a parasite fly (Evania apendigaster, FABR.), 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 (Jlndrena nigrocenea, STEPHENS). ' I had pre- viously,' he remarks, more than once observed upon other species something that I took to be a kind of Jlcarus which appeared to be immovably 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 had mistaken for an acarus! (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 I had drawn it out but a little way, I 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 animal 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 seemed dubious.'* Of the manner in which this singular insect (Stylops) introduced its eggs into the body of a bee nothing is yet known, and its rarity puts 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 Melittce, Kirby.) De Geer was one day much surprised to ob- serve a small white grub sucking the body of a young spider (Epeira diadema), having attached itself * Monogr. Ap. Angl. ii, 113. 68 INSECT TRANSFORMATIONS. firmly to the abdomen. Having put 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 circular 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 their 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 game, or similar substances, as her larva?, 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 their eggs on plants and trees where their young may eat abundantly of leaves or other parts c 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 indifferently of two or three sorts; while others take a wider range, and fix upon plants of very different 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 butterfly (Vanessa urticce) on any plant but the nettle; its congener, the painted lady (Cynthia cardui, STE- PHENS), though it prefers the spear-thistle, is some- times found on the nettle, as is the comma ( Va- nessa C. JUbuni), though it seems to prefer the hop; while we have found the eggs of the lackey moth (Clisiocampa ntustria) 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 (Jlrctia, Caja, STE- PHENS), will as readily select the nettle as the lettuce or dandelion.* It is worthy of remark that our native insects fre- quently 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 (Jlcheronlia Jltropos), 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 ( Solanum dulcamara). We 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 * J. R. 70 INSECT TRANSFORMATIONS. was transformed within the leaf, in a few days, into a pupa, and being put under a bell-glass, a small two- winged fly (Tephrilis Serratulce? ) 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 Serratula ?) 6, mined leaf of sow-thistle (Sonchus oleraceus). c c, mined leaf pf Senecio clegans, d f 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. Vapourer Moth. (Orgyia antiqua), male and liemale, the latter without wings j 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 Spal- lanzani and John Hunter, by exposing several spe- cies 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, 6 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 exposed to its influence in the open fields, on the naked 96 INSECT TRANSFORMATIONS. earth, or or on the branches of trees ? Yet, when the spring had tempered the air, these eggs produced as they usually did after the mildest winters. 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 eggs 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 enclosed 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 Ammonia), 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 to animalcula and insects. Germs in general can support 2 be- low 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-\vorm 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 can be resisted by their eggs. What can be the cause of so great a difference? Insects killed at 16 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 constitu- ent spirituous or oleaginous parts, or from some prin- ciple adapted to abate the power of cold.* If eggs do not freeze, it is probable the included embryos do not freeze. ' Is there anything wonderful, 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, con- centrated 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 I 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 the freezing point, the eggs of other animals may be hatched ? Nor should it surprise me to be told of animals whose eggs would produce at much greater cold, after knowing that there are plants, beings so similar to animals, and many of them, * In plain language, Spallanzani did not know what to make of the facts. 9 98 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.| 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 much greater number of insects, even of the smaller and more delicate kinds (Jlleyrodes, Corethra, Jllucita y &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 larvee of some small tipula (Boletophila?), which we found in abundance in Birch Wood, Kent, feeding on a fungus (Boletus fomentarius, FRIES), 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 * Spallanzani's Tracts, transl. by Dalyell, vol. i, p. 63. t Hunter on the Animal Economy. EFFECTS OF COLD UPON INSECTS. 99 migratory birds seem to have been aware of this abun- dance of insects by their 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 before their average time.* * J. R. CHAPTER V. Hatching of Insect Eggs. THE contents of an egg principally consist of nutriment adapted to the different parts of the germ which it contains the yolk for nourishing the soft parts; tfce 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 posi- tion for partaking of the repast, namely, in a par- ticular corner where it may breathe fresh air always communicated to the chamber of the egg by ven- tilatory 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 Malphigi 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 with the surface by the mobility of the slings and the weight of the oil-vessel tending downwards, how- ever 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 * Malpighi, de Ovo incubato , Leeuwenhoeck, Epist. phys. xl ; and Harvey, in Willoughby's Ornithol. c. iii. HATCHING OF EGGS. 101 yolk, of course the mere weighty part always de- scends, in every position of the egg, as far as they will permit, and the chick being thence prevented from sliding down, nourishes itself in security. We cannot, on account of their minuteness, as Cer- 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 em- bryo 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 indispensa- bly 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 in- crease 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 nume- rous 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. 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 then generally cease to feedV, they cannot possibly live long. A few instances, however, have been observ- ed, of insects performing something very similar to the 9* 102 INSECT TRANSFORMATIONS. incubation of birds, though we have the high authority of Fabricius, that < insects never sit upon their eggs. 7 * Upon the incontestable statements of two distin- guished observers of insects, Frischf and De Geer, the female of the common earwig (Forficula auricula- ria, 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 discovered a female ear- wig 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 4 , in collect- ing 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. J At another time, in the beginning of June, De Geer found under a stone a female earwig accompanied with a numerous brood of young, to all appearance newly hatched, and nestling under their mother like chickens under alien. These he likewise placed in a nurse-box with fresh earth ; but instead of burrowing into the mould, as he had expected, they crowded under the bosom and between the legs of their mother, who remained quiet and evi- dently pleased, suffering 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 apple ; and perceived that they grew from day to day, and * Fabricius, Philosoph. EntOmoI. Ixxvi. f Insecten in Deutschland, 4to, 1766. t De Geer, Mem., vol. Hi, p. 548. HATCHING OF EGGS. 103 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 disliking exposure to the light, they may, by chance, attempt to take shelter in the ear, the dis- agreeable 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, but no real injury. Drum of the ear, showing that there is no passage through it to the brain. Kirby and Spence are inclined to infer that a tree bug (Jlcanthosotnci grisea, STEPHENS) may also sit * J. R. 104 INSECT TRANSFORMATIONS. upon its eggs,* 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 around 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 beating her wings rapidly and incessantly, and never stirred from her young. But even all this, affec- tionately maternal as it must be considered, is far from authorizing the conclusion that she sits upon her eggs ; though it is certain she must remain near them till they are hatched, unless she belong to those mentioned by Busch as ovo-viviparous.j" 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 eggs. Many of these mothers, however, die before their young are hatched, all of them, per- haps, 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 little more than an average degree of coldness, every one of them died, some living a longer time, and others a shorter. J 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 cele- brated Harvey.^ ' In order,' says Swammerdam, * to * Intro, i, 358, and iii, 101. t Schneider, Europaische Schmetterlinge, i, 206. J. R. Harvey, De Generatione. HATCHING OF EGGS. 105 hatch her eggs the better, she carries them about as it were in a case, with wonderful solicitude and affec- tion ; insomuch, that when the skin forming this case, which hangs to the hinder part of her body, is by any accident broken off, the little insect seeks after it with as much earnestness and industry as a hen 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 ttys spider, which, though no less fierce and ferocious in aspect than her congeners, manifests an extraordinary change of mien when forcibly depriv- ed of her eggs. Then she instantly appears tame, stops to look around her, and begins to walk at a slow pace, and search on every side for what she has lost, nor will she even fly when one threatens 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 undisturb- ed, will leisurely attach it again 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 pit-fall of an ant-lion (Myrmelion formicariwn) ."\ 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 strug- gled hard to defeat the aim of the concealed depreda- tor ; but the gum which fastened her bag, not being calculated to withstand such violence, at length gave way, and the ant-lion was about to carry off the prize * Book of Nature, pt i, p. 24. t See Insect Architecture, p. 209. 106 INSECT TRANSFORMATIONS. in triumph. The spider, however, instantly regained it with her mandibles, and redoubled her endeavours to snatch the bag from her enemy ; but her efforts were vain, for the ant-lion, being the stronger, suc- ceeded in dragging it under the sand. The unfortu- nate mother, now robbed of her eggs, might have at least saved her own life, as she could easily have escaped out of the pit-fall ; 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, de- prived 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 portion 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 Geer;| ' without which,' says Kirby and Spence, c 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, (Euvres, vol. ii, p. 435. t De Geer, Mem. vol. vii, p. 194. J Introd. 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 been 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 riot beat her away from it after it was detached. ' By and by,' he continues, c I observed with surprise that she had abandoned and kept aloof from the very bag which she had previously defended with so much cou- rage 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 being 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 not abandon for some time, and for the purpose, as I was half inclined (pardon 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, which 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 the * J. R. t Bonnet, GEuvres, vol. ii, p. 440. 108 INSECT TRANSFORMATIONS. 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 removing the stranger, however, she showed the same indiffer- ence 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 hatching eggs oc- curs in several insects, thence termed ovo-viviparous, which retain the eggs within their bodies till they are hatched; and in this way they appear, like larger ani- mals, to produce young instead of eggs. We do not here allude to the cochenille insects formerly mention- ed; for though these cover their eggs with their bodies, it is after they are laid and imbedded in gos- samer. Neither can these singular insects be proper- ly said to sit upon their eggs, inasmuch as the mother always dies when she has finished laying. The gufTer (Blennius ovo-mviparus, 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 farther out to sea, that they may be out of the reach of their natural enemies. | Our common viper (Coluber berus, LINN.) is also ovo-viviparous, as are several other reptiles; though it is an exception to the general rule in this class. We caught a female of the nimble lizard (Lacerta agilis, LINN.) on a heath near Sorn, Ayrshire, 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 * J, R. t Lacepede, Poissoris, ii, p. 497. $ J. R. 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 thence led to put the question, whether such flies, under dif- ferent circumstances of temperature, do not sometimes produce young, and at other times deposit eggs."f He might as well, says R aumur, have asked whether, in certain circumstances, a hen, instead of laying eggs, should bring forth chickens. The fact, on the contrary, has been ascertained by Rf aumur, 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 simi- lar 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 Ccesar, LINN.), 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. t Redi, Esperienze intorno alia Gen. degP Insetti, 4to, 1668. t Annales des Sciences Naturelles. Page 3. TOL. VI. 10 110 INSECT TRANSFORMATIONS. blue -bottle, rather longer and more slender, and black, with lighter stripes on the shoulders, is not blue in the abdomen, but grayish black, and all over chequered with squares of a lighter colour. This chequered blow- fly (Sarcophaga carnaria, MEIGEN) does not even belong 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 offensive parts of carcasses. The arrangement of the numerous minute Iarva3 in the pouch is very remarkable, and resembles the coil of a watch-spring or a roll of ribbon. R aumur had the patience and perseverance to uncoil this multitudinous 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-third of an inch, A, the chequered blnw-fly B, the abdomen of the chequered Mow-fly, opened and magnified, showing the coil of young larva 1 . C, the coil of larvqp partly unwound. OVO-VIVIPAROUS INSECTS. 1 1 1 and he computed that there were about 20,000 young in the coil.* When this extraordinary fecundity is considered, we need not wonder at the countless swarms which appear as if by magic upon a joint of meat du- ring hot weather. Like most female insects, the mother-fly dies in a few days after giving birth to her numerous brood; but, unlike 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, R aumur 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 larvae, and closed the natural opening of the pouch with sealing-wax, so that it was impossi- ble 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 shut up for ten days. Another large gray fly with brick-red eyes (species A, large gray blow-fly, with the abdomen opened, showing the young maggots. B, breathing apparatus of the maggot of a large gray blow- fly- * Reaumur, Mem. iv, 417. 112 INSECT TRANSFORMATIONS. not ascertained) was discovered by Rt'aumur to be ovo- viviparous; but the embryo flies were not arranged 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 appara- tus, which, when shut, as it could be at pleasure, ap- peared in the form of a crown. Amongst several other ovo-viviparous flies discovered by R aumur, there was a very minute tipulidan gnat (species not ascertained) with a jet-black body, white wings, and beaded antemue, 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 cir- cumstance, that 'the minute and the grand are nothing, or rather are the same, to the Author of nature.' The numerous genus Aphis presents the singular anomaly of producing eggs in the autumn and living young during summer, and, as Curtis tells us, even during winter in green-houses. De Geer, however, 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 ascer- tained the curious fact, that in three months nine gene- rations of these insects may be produced in succes- sion, 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 pro- duced 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 Insectes, iii, 70. EGGS GF APHIDES. 1 13 Bonnet, however, whose opinion is entitled to considerable authority, seems to think that the eggs 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 egg, surrounded by food, by means of which it is de- veloped and supported. It is nothing more, he con- jectures, than an asylum of which the aphides ap- pearing 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 mo- thers are not then truly oviparous, even in autumn, when they deposit these pseudo-eggs; since their young are almost as perfect as they ever will be, in the asy- lum 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- quc nee, 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 Feb- ruary, and in 1830 we had a brood of several hundreds produced of the oak aphis (Jlphis Quercus).* The failure on the part 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 Huber's own words. ( One day in November,' says he, ' anxious to know if the yellow ants (Formica flava) began to bury themselves in their subterranean chambers, I de- stroyed, with care, one of their habitations, story by * J.R. VOL. vi. 10* 114 INSECT TRANSFORMATIONS. story. I had not advanced far in this attempt, when I discovered an apartment containing an assemblage of little 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 d welling 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 different 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, grayish, 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 then! highly ; after having visited them, they placed one part in the earth, but I witnessed the attention they bestowed upon the rest ; they approach- ed them, slightly separating their mandibles; passed their tongue between each, extended them, then walk- ed 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 affectionate regard, conveyed them with extreme tenderness to the little 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 ^ jth the origin of those of which I have just spoken, and by chance discovered they contained little aphides; but it wab not these in- dividual 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- hill, 1 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. I 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 themselves 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 1C. 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 e<*gs they lie in multi- tudes, i I suppose,' says Derham, < by way of in- cubation. 'I * I have observed,' adds Sir E. King, 1 in summer, that in the morning they bring up those of their young called ant -eggs (cocoons] 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- poboscidce, LEACH) resemble the aphides in some points of their economy, though in others they are singularly peculiar. R aumur 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. R aumur 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. llth ed. t Phil. 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 after- wards 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 pa- rents. He calls them spider flies, from their resem- blance 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 (Hippoboscidcp, Leach.) We have the more willingly introduced this sub- ject here, that another fly (Crattrina Hirundinis y OJ.FERS), 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 R aumur, 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 ex- istence, lives by sucking the blood of the swallows, as the one first mentioned sucks the blood of horses, horned cattle, and ; it is also said, of man. 118 INSECT TRANSFORMATIONS. The effect of heat upon the eggs of insects has been carried much farther than in the experiments just alluded to of R aumur and Bonnet.* Spallanzani 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 polychlorosl) perfectly corresponded with those of the silk-worm. In the case of the eggs of the blow-fly (Musca vomitoina) 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 pupae were produc- tive at 104 and 106, but not at lll.t If these experiments may, as we believe they may, be relied on, we have some reason to doubt that ' the eggs of the musca vomiloria, 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 stakes, in a heat not merely of 212, but of three or four times ; and yet, instead of being hereby destroyed, we * See Insect Architecture, p. 24. t Spallanzani, Tracts by Dalyell, vol. i, p. 85. EFFECTS OF HEAT UPON EGGS, 119 sometimes find them quickened by this very exposure into their larva or grub state.'* It would have been well if some more accurate authority had been given for so miraculous a fact than this general statement: the appearance of maggots on broiled meat, from which the inference is apparently made, seems rather to indicate that eggs, or more probably ovo-viviparcus larvae, 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 egg is feeble, or at least lethargic, in comparison with that of the animal produced; and that animals, when in a state of very feeble animation, resist external injuries with more impunity than when very vivacious. We once saw a very delicate young girl, emaciated with scro- fula, have her leg amputated without even heaving a sigh; while a robust Irish labourer, who underwent the same operation immediately after her, roared like a bull. Experiments prove that the fluids of eggs, and con- sequently of their germs, are more abundant than in vegetable seeds; and this excess of fluid may tend to destroy the germ more readily, from heat expanding the fluids, and thus putting them in motion: for then they must strike violently against the tender parts of the germs, arid rupture and destroy them. Hence seeds exposed to heat are killed at lower degrees in water, than if dry, in the same way as ice will melt sooner in warm water than in air of equal temperature. f * Good's Book of Nature, vol. i, p. 221. 1st edit. t Spallanzani, Tracts by Dalyell, vol. i, p. 43. 120 INSECT TRANSFORMATIONS. In the practical management of the eggs of the silk- worm, Count Dandolo directs the temperature of the stove-room to be 64 when they are first put in. c The third day the temperature should be raised to 66; the fourth day to 68; the fifth day to 71; the sixth day to 73; the seventh day to 75; the eighth day to 77; the ninth day to 80; the tenth, eleventh, and twelfth days to 82. When the temperature of the stove-room is raised to 75, it is advantageous to have two dishes, in which water may be poured, so as to offer a surface of nearly four inches diameter. In four days there will have taken place an evaporation of nearly twelve ounces of water; the vapour, which rises very slowly, moderates the dryness which might occur in the stove-house, particularly during a north- erly wind: very dry air is not favourable to the devel- opment of the silk-worm.'* Damp or stagnant air, or sudden changes of temperature, either high or low, are exceedingly injurious to the hatching of eggs. From some very curious experiments of Michelotti, it appears that exposure to light is by no means favour- able to the hatching of eggs This ingenious natural- ist i sclosed a number of eggs in glass vessels, admit- ting the light to one series and excluding it from another, similar in every other particular. The result was, that few or none of the eggs exposed to light were hatched, while those in the dark were almost all fertile. He arrived at the same results in his experi- ments upon vegetable seeds. "f Kirby and Spence justly remark, that these curious facts may account for so many insects fastening their eggs to the under sides of leaves, and may be the final cause of the opaque horny texture of those exposed in full day.J Among the singular circumstances in which insects differ from the larger animals, we may reckon that * Count Dandolo, on Silk- Worms, Eng. trans., p. 55. t Philosophical Mag., vol. ix, p. 244. | Introduc. iii, p. 77. INCREASE IN SIZE OF EGGS. 121 of the eggs of some increasing in size during the pro- cess of hatching. The fact appears to have first been noticed by the celebrated Vallisnieri in his observa- tions on saw-flies (Tenihredinidcz, LEACH).* Other instances were subsequently discovered by R aumur, De Geer, Derham, R' sel, and the younger Huber. ' It ought not,' says R aumur, speaking of gall flies ( Cympidce, WEST WOOD), ' to be passed in silence, that the egg which I found in the gall appeared to me considerably larger than the eggs of the same spe- cies when they proceed from the body of the fly, or even when they are taken from the mother fly near the time of their being laid. The whole of those I took front the mother flies which I killed were remarkably Generation of a water-mite (Hydra-hna alstergens). a a, the water scojpion, in whose body the mite fixes her eggs. 6 b, a magnified view of one of its claws, c, a tooth-like process for restraining the motion of the joint.