182 



APHANIPTEKA. 



which are called nits, to the hairs or feathers upon which 

 they climb. 



Okder Aphaniptera.* 



These insects, like those belonging to the pre- 

 ceding order, are wingless, but they undergo a meta- 

 niorphosis. Their body is very much compressed at 

 the sides, and the legs adapted to leaping. The 

 mouth is provided with lancets, and performs the 

 functions of a sucking apparatus. In their larva 

 state they resemble little w^orms, and are quite 

 destitute of feet. The perfect insect lives upon 

 quadrupeds and birds. This order comprehends — 



The Fleas (Pulex). The common flea {Pidex irrttans) 

 lives upon dogs, cats, and men, whose blood it sucks. 

 The female lays about a dozen eggs, white and slightly 



Fig. 143.— metamorphoses of the fle.\. 



viscid. These eggs give birth to larvfe, which are very 

 active. They roll themselves up into a spiral circular form, 

 and wriggle about like minute serpents. In about twelve 

 days these larvae enclose themselves in a little cocoon, 

 where they become nymphs, and in about twelve days more 

 issue forth in their perfect state. 



* acpau^s, aplianes, hidden ; Trr^pov, pteron, a wing. 



