4 8 



ENTOMOLOGY 



use the term apodemes for furcae and others apply the term apodeme 

 to any of the three kinds of ingrowths. 



Legs. In almost all adult insects and in most larvae each of the 

 three thoracic segments bears a pair of legs. The leg- is articulated to 

 the sternum, episternum and epimeron, partly by means of small 

 articular sclerites (one of which, the trochantin, is shown in Fig. 63) 

 and consists of five segments (Fig. 62), in the 

 following order : coxa, trochanter, femur, tibia, 

 tarsus. The coxa is the basal segment. The 

 trochanter is small and in parasitic Hymenop- 

 tera consists of two subsegments. The femur 

 is usually stout and conspicuous, the tibia 

 commonly slender. The tarsus, rarely single- 

 jointed, consists usually of five segments, the 

 last of which bears a pair of claws in the adults 

 of most orders of insects and a single claw in 

 larvae; between the claws in most imagines is a 

 pad, usually termed the pulvillus, or empodium. 

 Adaptations of Legs. The legs exhibit a 

 great variety of adaptive modifications. A 

 walking or running insect, as a carabid or 

 cicindelid beetle (Fig. 64, A) presents an aver- 



FIG. 6 1. Transverse sec- a g e condition as regards the legs. In leaping 

 tions of the thoracic segments insects (grasshoppers, crickets, Haltica) the 



of a beetle, Goliathus, to show 



the endoskeietai processes, hind femora are enlarged (B) to accommodate 

 nx- PT c* h mlt&thoT S a h ^ the P owerful extensor muscles. In insects that 

 furcae; ad, apodeme; p, make little use of their legs, as May flies and 



phragma. After KOLBE. . ,. , 



Tipulidae, these appendages are but weakly 



developed. The spinous legs of dragon flies form a basket for catching 

 the prey on the wing. Modifications of the front legs for the 

 purpose of grasping occur in many insects, as the terrestrial 

 families Mantidae (C) and Reduviidae and the aquatic families 

 Belostomidae and Naucoridae (D). Swimming species present special 

 adaptations of the legs (Fig. 231), as described in the chapter 

 on aquatic insects. In digging insects, the fore legs are expanded to 

 form shovel-like organs, notably in the mole-cricket (Fig. 64, E), in 

 which the fore tibia has some resemblance to the human hand, while 

 the tarsus and tibia are remarkably adapted for cutting roots, after 

 the manner of shears. The Scarabaeidae have fossorial legs, the anterior 

 tarsi of which are in some genera reduced (F) or absent; they are rudi- 



