io6 



ELEMENTA RV ENTOMOLOG Y 



adapted to their surroundings. Other members of this family, called 

 psocids, are winged and look much like large plant-lice. The wings 

 are of a dusky color, have a very characteristic venation, and are 

 held roof-shaped over the back. Psocids feed on lichens and decay- 

 ing wood and are fre- 

 quently found in large 

 masses on fences or 

 tree trunks, where they 

 are suspected of doing 

 mischief, but they are 

 entirely harmless and 

 need not be disturbed. 



The biting bird-lice 

 (Mallophaga) are curious 

 looking, wingless para- 



FIG. 138. Biting lice (J/^/^^). (Greatly enlarged) sites whkh ^^ 



a, turkey-louse (Gomodes sty lifer Nitsch) (after Cuvier): r f u r nnil 1 rrv 



b, the biting dog-louse (Trichodectes latus Nitsch) (after [ Poultry 

 Denny). (From Osborn, United States Department of birds, while SOIHC inf CSt 



Agriculture) -, , 



sheep and mammals. 



They have biting mouth-parts and feed on feathers, hair, and bits 

 of skin, thus differing from the true lice (see p. 121), which have 

 sucking mouth-parts with which they extract the blood. The flat- 

 tened bodies and curiously shaped heads enable one to identify 

 them readily. A dust bath, with a frequent thorough cleansing of 

 the poultry house by spraying with kerosene and then whitewash- 

 ing, will usually prevent serious annoyance to poultry. 



