A text-book of entomology, including the anatomy, physiology, embryology and metamorphoses of insects, for use in agricultural and technical schools and colleges as well as by the working entomologist . ape of thetibia in these insects, which are flattened withseveral broad triangular spines, bears a strong resem-blance to the nails or claws of the fossorial limbs of those mam-mals which dig in hard soil, such as the armadillo, manis, aardvark,and Echidna. The principle ofmodification by disuse is wellillustrated in the following many butterflies the forelegs are small and shortened,
A text-book of entomology, including the anatomy, physiology, embryology and metamorphoses of insects, for use in agricultural and technical schools and colleges as well as by the working entomologist . ape of thetibia in these insects, which are flattened withseveral broad triangular spines, bears a strong resem-blance to the nails or claws of the fossorial limbs of those mam-mals which dig in hard soil, such as the armadillo, manis, aardvark,and Echidna. The principle ofmodification by disuse is wellillustrated in the following many butterflies the forelegs are small and shortened, andof little use, and held pressedagainst the breast. In the Lycse-nidse the fore tarsi are withoutclaws; in Erycinidae and Liby-theidae the fore legs of the malesare shortened, but completely de-veloped in the females, while inthe Nymphalidae the fore legs inboth sexes are shortened, consist-ing in the males of one or twojoints, the claws being absent in the females. Among moths loss of the fore tarsi is less frequent. J. B. Smith * notices the lack of the fore tarsi in the male of a deltoid, Litognatha nubilifasciata (Fig. 113), while the hind feet of i Ent. Amer., v, p. 110, PI. II, Fig. 7. B. FIG. 112. — Fore leg of the mole-cricket: ^4,B, inner, aspect; e, ear-slit. — After MECHANICS OF WALKING 103 Hepialus hectus are shortened. In an aphid (Mastopoda pteridis,CEsl.) all the tarsi are reduced to a single vestigial joint (Fig. 114). Entirely legless adult insects are rare,and the loss is clearly seen to be an adapta-tion due to disuse; such are the females ofthe Psychidae, the females of severalgenera of Coccidse (Mytilaspis, etc.), andthe females of the Stylopidae. Apodous larval insects are common, andthe loss of legs is plainly seen to be asecondary adaptive feature, since there areannectant forms with one or two pairs ofthoracic legs. All dipterous and siphonap-terous larvae, those of all the Hymenopteraexcept the sawflies, a few lepidopterouslarvae, some coleoptero
Size: 1477px × 1692px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectinsects
