PARASITES AND PARASITIC DISEASES OF HORSES 47 
when they drop to the ground, crawl up into dry, protected places 
above the ground, and again molt. The skin of the nymph is 
covered with spines, but that of the mature tick is smooth. So far as 
is known the adult tick does not attach itself to animals nor does it 
take food. Mating and egg laying take place off the animal, and 
when egg laying is completed the female dies. The eggs may hatch 
as early as 10 days after they are laid. Shortly after hatching the 
seed ticks are ready to attach themselves to any suitable host. They 
may live as long as three months if no host is found. 
Symptoms.—W hen animals are grossly infested and the ear canals 
packed full of ticks the parasites are visible on superficial examina- 
tion, but when the degree of infestation is light or moderate the ticks 
may be overlooked. They usually attach themselves in the deep 
folds of the ear or crawl into the ear canal and follow it inward, 
sometimes as far as the eardrum. As the ticks increase in size and 
others enter, they and the excretions, with the wax from the ear, 
accumulate in masses or plugs sufficient in some cases to close up the 
ear passages completely. These conditions give rise to various 
symptoms. ‘The infested animal usually shakes its head and re- 
peatedly turns it from side to side, meanwhile inverting, or turning 
down, first one ear and then the other. When irritation and itching 
are more intense on 
one side the animal yt 
often turns its head : Te are 
so that the more se- a 
riously affected ear Figur 32.—Har probe made of baling wire 
is held downward. ! 
There is a tendency to rub and scratch the ears, and young animals 
often run as though endeavoring to relieve the nervous tension. 
In all cases where ear-tick infestation is suspected the animals 
should be examined, and if no ticks are visible the ears should be 
probed. A convenient and effective instrument for probing the ears, 
removing ticks from the ear canals, and breaking down masses of 
ear wax and ticks may be made from a piece of ordinary baling 
wire, as shown in Figure 32, the loop end being used for dislodging 
the ticks. 
Treatment.—Complete eradication of spinose ear ticks is a diffi- 
cult matter, on account of the habits and great vitality of the 
ticks and the wide range of animals which they may infest. Results 
of investigations conducted by the Bureau of Animal Industry have 
shown that dipping in any of the known dips or the injection into 
the ear passages of bland oils, crude petroleum, or various dips, etc., 
is not effective in killing the ticks or causing them to leave the ears. 
Gasoline and kerosene when applied undiluted kill the ticks, but 
cause blistering of the skin and are not suitable for use on horses. 
Chloroform, undiluted or mixed with a bland oil, is commonly used. 
on horses and dogs and is effective. Such substances as chloroform 
evaporate rapidly, and therefore afford no protection against 
reinfestation. 
The remedy for ear ticks formulated and thoroughly tested by the 
Bureau of Animal Industry consists of a mixture of two parts by 
volume of ordinary pine tar and one part by volume of cottonseed 
oil. In mixing the ingredients add the cottonseed oil to the pine tar 
