PARASITES AND PARASITIC DISEASES OF HORSES 45 
psoroptic mite. Chorioptic mites live on the surface of the skin and 
produce lesions similar to those of psoroptic mange. 
The lesions of chorioptic mange are usually confined to the lower 
part of the limbs around the foot and fetlock: Occasionally the 
mites spread over the legs above the hocks, and may reach even the 
thighs and abdomen, but usually the disease remains localized around 
the feet. 
Infested animals paw and kick and rub the pastern with the oppo- 
site foot and often try to bite the affected parts. Some of the hair 
comes out and the skin has the thickened and hardened condition 
characteristic of scabies. 
The remedies recommended for sarcoptic mange are effective in 
eradicating foot mange. The affected areas should be well soaked in 
warm lime-sulphur dip, and the treatment repeated every 10 days 
until a cure is effected. Driving the horses through a shallow wad- 
ing tank filled with dip is a quick and effective method of treatment 
for foot mange. 
TICKS 
There are many different kinds of ticks which may attack horses, 
but since the habits and life cycles of the different species vary 
greatly discussion in this circular is necessarily hmited to general 
information, except for the ear tick, which is discussed more fully. 
When only a few ticks are found on horses they may be removed 
by hand or covered with crude petroleum, cylinder oil, kerosene, or 
other oil, which usually causes them to detach and drop to the 
ground. In removing ticks by hand the writer has observed that 
they may sometimes be detached without leaving the head embedded 
in the skin by twisting them around as they are pulled loose. 
In the southern and western parts of the United States it is not 
uncommon for horses to become grossly infested with ticks. In 
some sections the infestation may occur only infrequently; in others 
it may occur more or less regularly each year. In the region in- 
fested with cattle-fever ticks where eradication work is in prog- 
ress tick-infested horses are dipped in arsenical solution to kill the 
parasites. 
In any locality where the horses become infested with ticks and 
the infestation is extensive the State livestock sanitary authorities 
should be notified in order that the ticks may be identified and 
proper measures taken for control. Control or eradication methods 
to be successful must be based on a knowledge of the life history 
and habits of the tick involved. 
SPINOSE EAR TICK 
Nature and habits—The spinose ear tick (Ornithodoros méqgnint) 
is prevalent on horses in the Southwest and causes serious damage to 
the livestock industry. Spinose ear ticks (fig. 31) enter the ears of 
animals as small, 6-legged seed ticks and attach themselves in the 
external canal well below the hair line, where in a week or two they 
become engorged larve. The engorged larve molt to form nymphs 
or young ticks having eight legs. The young ticks remain in the 
ears from one to seven months, or until fully grown and engorged, 
