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 . ter 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 Stylop
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 . ter 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 coleopterous, as those of theRhyncophora, Buprestidse, Eucnemidse, andother families, and many Cerambycidee arewithout any legs. In EupsaUs minuta,belonging to the Brenthidae, the thoraciclegs are minute. The legs of larvae end in a single claw, upon the tips of which theinsect stands in sh- FIG. 113. — Leg- of Litognatka :cee, coxa; /, femur; I, tibia; ,its epiphysis, and .sA, its shield-likeprocess. The tarsus entirely want-ing. — After Smith. c. Locomotion (walking, climbing, and swimming) Mechanics of walking. --To Graber we owe the best exposition ofthe mechanics of walking in insects. The first segment of the insect leg, he says, upon which the weight ofthe body rests first of all, is the coxa. Its method of articulation is very differ-ent from that of the other joints. The enartlirosis affords the most extensiveplay, particularly in the Hymenoptera and Diptera. In the former the development of their social conditions is very closely con-nected with the freest possible use of the legs, which serve as hands. In thebeetles, however, which are very compactly bui
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectinsects
