io6 



ELEMENTARY ENTOMOLOGY 



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 

 (Mallophagctyare curious 

 looking, wingless para- 

 sites which infest the 



a, turkey-louse (Goniodes stylifer Nitsch) (after Cuvier); r f ^ r nrm U rv ~ nr l 



6, the biting dog-louse (Trichodectes latus Nitsch) (after leatl * P oul try an 



Denny). (From Osborn, United States Department of birds while SOme infest 



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. 





FIG. 138. ^Bit\r\g\\ce(Mallophaga). (Greatly enlarged) 



