110 



BITING-LOUSE OP 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 lafu^s 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 slighth^ 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 strongW curved claw upon each 



X>^ 



Fig. 78.— Biting louse 

 of ciog. Greatly en- 

 larged. After Nitzsch. 



r:T 



Fig. 79.— Biting- 

 louse of cat. Greatly 

 enlarged. Original. 

 After Nitzsch. 



tarsus. The ten-jointed, elongated-oval abdomen is covered 

 with bristles, and is light yelloAv; the thorax is darker. 

 Length 1 to 1.5mm., seldom 2mm. Fig. 78 is copied from 

 Nitzsch's Insecta epizoa., edited by Giebel. 



The early stage of a tape-worm {Twnia cucumerina or 

 D'qjijUd'unn vanhuim L.) occurs in this louse. The dog, by 

 crushing this source of irritation with the teeth, can thus 

 directh' become infected by this tape-worm. 



