272 ZOOLOGY 



with imperfect metamorphosis, and are remarkable for 

 their social life in large colonies. The anterior and 



posterior wings are similar 

 to one another. 



Order Corrodentia 



The book lice (which 

 are not lice) and their rela- 

 tives ; very small insects 

 with long, slender antennae 



From Bulletin 67, U. S. National Museum and incomplete metamOr- 

 FIG. 86. A "tree louse, " Psocus venosus phosis. In One grOUp the 



wings are well developed, 

 in another group they are absent. 



Order Mallophaga 



Biting lice Biting lice, abundant on birds, though some genera 

 infest mammals. They are wingless. 



From Bulletin 67, U. S. National Museum From Bulletin 67, U. S. National Museum 



FIG. 87. A bird louse, Goniodes fold- FIG. 88. A head louse, Pediculus capitis 

 cornis (Mallophaga). (Siphunculata) . 



Order Siphunculata 



True lice The true lice, including those infesting man. The 



mouth is beaklike, adapted for sucking. 



