74 



PARASITES OF THE DOMESTIC ANIMALS 



Biting lice are less common upon horses than suctorial. They are not 

 often found on the upper parts of the body, more frequently occupying 

 the regions of the neck, breast, and between the fore and hind legs. 

 They cause less pruritus than the sucking lice, though the animals will 

 frequently rub bare places at the regions infested. Both forms may 

 coexist upon the same animal. 



Pediculosis of the Ox 



Two species of suctorial lice inhabit the ox, Hcematopinus eurysternus, 

 — the short-nosed ox louse, and Linognathus vituli, — -the long-nosed ox 

 louse. Of the biting species there is but one, Trichodedes scalaris. 



1. Haematopinus eurysternus. Pediculidae (p. 70). — Head relatively 

 short and broad, rounded in front; thorax about twice as wide as long. 



Fig. 40. — Hsematopiuus eurysternus: a, female; b, rostrum; c, 

 ventral surface of the last segments of male; d, same of female; e, egg; 

 f, surface of same greatly enlarged (after Osborn, Bui. No. 5, Bureau 

 of Entomology, U. S. Dept. of Agr.). 



widest posteriorly. The abdomen is oval and much larger than that of 

 the sucking louse of the horse. On the lateral margin of each abdominal 

 segment is a slightly colored tubercle. In the female two black blotches 

 are laterally located on the terminal segment. The general color is 

 yellowish gray. The female is 2 to 3 mm., the male 2 mm. in length 

 (Fig. 40). 



2. Linognathus vituli (Haematopinus vituli). Pediculidae (p. 70). — 

 Somewhat smaller than the preceding. The head is long and narrow 

 and somewhat sunken in the thorax, as in a notch. The thorax is about 

 as broad as long. The abdomen, like the head, is long and narrow, 

 giving to the entire insect a long and slender appearance. The general 

 color is a deep chestnut. The female is 2.5 to 3 mm., the male 2 to 2.5 

 mm. in length (Fig. 41). 



