Book-lice and Bark-lice; Biting Bird-lice 
I 2 I 
Pigeons are almost always infested by a long and very slender louse, 
Lipeunis baculus (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. 
All of the species infesting domestic mammals belong to the genus Tricho- 
dectes. Dogs are often infested by Trichodectes latus (Fig. 149), a short, 
wide-bodied species about 1 mm. long; while cats are less often infested by 
T. subrostratus, distinguishable by the rather pointed head with a short, 
longitudinal furrow on the under side. Horses and donkeys are troubled 
by two or three species, of which T. pilosus , a hairy form with antennae 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 
t 
Fig. 154. 
Fro. 153.—A biting louse of gulls, Nirmus felix, male. (Natural size indicated by line.) 
Fig. 154.—Giant bird-louse of the albatrosses, Ancistrona gigas, male. (Natural size 
indicated by line.) 
been found on the bear, raccoon, fox, coyote, weasel, gopher, beaver, deer, 
skunk, and porcupine. Gyropus, the other mammal-infesting genus of 
Fig. 153. 
