PARASITES AND PARASITIC DISEASES OF HORSES 



37 



EXTERNAL PARASITES OF HORSES 



Horse Lice 



Usually lice are restricted to one host species or to closely related 

 species, and horse lice will not live on animals other than horses, 

 mules, and asses. Three kinds of lice are commonly found on horses 

 in the United States. The first and most important of these is the 



M 



- m 



Figure 24- — Sucking louse of horses {Haematopinus asint): A, Male; B, female 



(Magnified 2 5 times.) 



blood-sucking species known technically as Haematopinus asini. The 

 two other species, Bovicola pilosa and B. parumpilosa, are biting lice. 

 The sacking louse of the horse is easily distinguished from the 

 biting species. It is much larger and has a long, pointed head, 

 whereas the biting lice have short, blunt, rounded heads (figs. 24 

 and 25). The sucking louse apparently causes more damage than 

 the biting lice and it is more difficult to eradicate. 



NATURE AND HABITS 



The eggs or nits of the sucking louse are attached firmly to the hairs, 

 usually close to the skin, and they hatch on the animal in from 11 to 20 

 days, the majority hatching in from 12 to 14 days. The young lice 

 reach maturity and the females begin laying eggs when they are 11 or 

 12 days old. The lice pass their lives on horses, and can live only 

 about 2 or 3 days when off a host animal. 



