34 CIRCULAR 148, U. §. DEPARTMENT OF AGRICULTURE 
Keep stables clean; remove manure often, daily if possible; supply 
clean bedding and change it often; and supply clean water. 
Feed from boxes well raised above the ground and from overhead 
racks. Do not feed from the ground, because the feed will become 
contaminated with manure. 
Do not spread fresh manure on pastures. Hold stable manure, 
preferably in double-walled, closed containers, until it has under- 
gone a heating process. If you have an open manure pile, turn the 
outer few inches of the manure once a week. Bury it under the 
inner portion. If you have no facilities for keeping manure, haul 
it to areas used by animals other than those that produced the 
manure or plow it in for field crops. 
Take steps to reduce the fly nuisance by storing manure in closed 
containers or use flytraps or other preventive measures recommended 
by the United States Department of Agriculture. 
Remember that foals require special treatment to tide them over 
the critical period of infancy. If you expect to raise sound horses, 
protect the foals. 
Consult a veterinarian when your horses require medicinal treat- 
ment for the removal of parasites. 
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 
blood-sucking species known technically as Haematopinus asini. 
The two other species, 7’7ichodectes pilosus and T. parwmpilosus, 
are biting lice. 
The sucking 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. 
The biting lice of horses deposit their eggs in the same general 
manner as the sucking louse. The period of incubation is probably 
from 8 to 10 days. These lice may live as long as 10 days when 
separated from the host animal if kept on tufts of hair, but most 
of them die in 5 or 6 days. 
5 By Marion Imes. ; 
6From photomicographs by W. T. Huffman, of the Bureau of Animal Industry. 
