156 



INSECT TRANSFORMATION 



blood can be sucked in. The legs are short and robust, the 

 shin being immensely broadened towards its tip which is 

 produced into a blunt outgrowth bearing strong spines 

 (Fig. 89 f). Just at the base of this is a ridge or pad beset 

 with spines short, fine and sharp. The foot-region consists of 

 one very short segment which bears a single strong curved 

 claw so arranged that in conjunction with the pad and spines 

 of the shin, it clasps a hair of the host-animal. These struc- 

 tural details have been mentioned to emphasize the fact that 

 lice are parasitic insects, which, while degraded on account 

 of the absence of wings, are very specially adapted for clinging 



FIG. 89. CATTLE-LOUSE (Haematopinus eurystenius). 



a, female. x 15. b, rostrum with hooks. x 120. c, ventral view of male's abdominal 

 extremity ; d, of female's, x 30. e, egg attached to hair, x 15. /, tip of shin with foot, 

 claw and pad. x 120. g, young, x 30. a e, from Osborn, U.S. Dept. Agric. Ent. Bull. 5. 



to the hairs of large animals and sucking their blood. The 

 adult male louse has an extensive, strongly chitinized plate 

 or tube below the abdomen (Fig. 89 c) protecting the genital 

 armature, while the female has, at the tip of her abdomen, 

 a pair of strong claspers (Fig. 89 d), which hold the eggs. A 

 louse's egg-case (Fig. 89 e) is a distinctly graceful, sculptured 

 object attached after laying, by means of secreted cement, to 

 a hair of the host-animal. From this egg is hatched a young 

 insect (g) which in the general form of its body, its highly 

 specialized suctorial mouth and clinging feet is a nearly exact 

 miniature of its parent. Only the distinctively sexual 

 structures concerned with reproduction are wanting, and 



