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



bands, and a white region in the middle of the abdomen. Trinoton luridum 

 is another common duck-louse unusually large, being from 4 to 5 mm. (5 in.) 

 long and readily distinguished by the triangular 

 head with lateral swellings, and the abdomen with 

 pronounced blackish-brown transverse bands. 



Fig. 150. 



Fig. 148. 



Fig. 152. 



Fig. 148. — .\ biting louse of pigeons, Lipeurus baculus. (Natural size indicated by line.) 



Fig. 149. — Biting louse of the dog, Trichodectes lalus. (.^ftcr Nitzsch; natural size, 

 I to 1.5 mm.) 



Fig. 150. — Biting lou.se of the horse, Trichodectes parumpilosus, male, (.\flcr Morse; 

 natural size shown by line.) 



Fig. 151. — Biting louse of cattle, 7"r/<:/iorfec/«j scalaris. (.\fter Lugger; natural size, 1.5 

 to 2 mm.) 



Fig. 152. — Biting louse of fringilline birds, Docophorus communis. (Natural size in- 

 dicated by line.) 



