Book-lice and Bark-lice; Biting Bird-lice 121 



Pigeons are almost always infested by a long and very slender louse, 

 Lipciirus bacillus (Fig. 148). The head and thorax are reddish brown, 

 while the abdomen is dusky with darker segmental blotches. This bird- 

 louse was described and named more than two hundred years ago. 



AH of the species infesting domestic mammals belong to the genus Tricho- 

 dectes. Dogs are often infested by Trichodecks latus (Fig. 149), a short, 

 wide-bodied species about i mm. long; while cats are less often infested by 

 T. subrostraius, distinguishable by the rather pointed head with a short, 

 longitudinal furrow on the under side. Horses and donkeys are troubled 

 b}- two or three species, of which T. pilosits, a hairy form with antenna; rising 

 near the front of the head, and T. parumpilosus (Fig. 150), a broader-bodied 

 form with head larger and less flatly rounded in front, are most common. 

 Trichodectes scalaris (Fig. 151) infests cattle the world over, while sheep 

 and goats have species peculiar to themselves. Comparatively few species 

 of Trichodectes have been recorded 

 from wild mammals, but this is 

 simply because they have not been 

 sought with care. Species have 





ny\\i ,. , :.:.^\^ 



Fig. 



153- 



Fig. 154. 



F'C- I53- — A biting louse of gulls, !\,'!rmus jelix, male. (Xatural size indicated by line.) 

 Fig. 154. — Giant bird-louse of the albatrosses, Ancislrona gigas, male. (Natural size 

 indicated by line.) 



been found on the bear, raccoon, fo.x, coyote, weasel, gopher, beaver, deer, 

 skunk, and porcupine. Gyropus, the other mammal-infesting genus of 



