110 BITING-LOUSE OF DOG. 
and the parasites belonging here are characterized by pos- 
sessing three-jointed feelers, while all others have five-jointed 
ones. 
THE BITING-LOUSE OF THE DOG. 
( Trichodectes latus Nitzsch). 
This parasite is found not very commonly upon our 
dogs. It shows, apparently, a preference for puppies, and is 
said to migrate from older to younger hosts in large num- 
bers when opportunity offers. Its hairy head is large, al- 
most square, but slightly rounded in front, and of a dark 
yellow color, with four brown marginal spots. The three- 
jointed feelers are inserted in a depression, behind which is a 
dark spot. The thorax is composed of two joints of equal 
length, of which the former is the narrower. The legs are of 
equal length, thick, with a strongly curved claw upon each 

Fig. 79.—Biting- 
Fig. 78.— Biting louse louse of cat. Greatly 
of dog. Greatly en- enlarged. Original. 
larged. After Nitzsch. After Nitzsch. 
tarsus. The ten-jointed, elongated-oval abdomen is covered 
with bristles, and is light yellow; the thorax is darker. 
Length 1 to1.5mm., seldom 2mm. Fig. 78 is copied from 
Nitzsch’s /nsecta epizoa, edited by Giebel. 
The early stage of a tape-worm (Ziwnia cucumerina or 
Lipylidium caninum L.) occurs in this louse. The dog, by 
crushing this source of irritation with the teeth, can thus 
directly become infected by this tape-worm. 
