E-695 July 1946
United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
CCTROL OF TE EAR TICK
By C. S. Rude and H. E. Parish
Division of Insects Affecting Man and Animals
The ear tick (Ornithodoros menini Dug"s) in widely distributed in the United States, Mexico, an Centrii and South America. In the United States it is most abundant in the semiarid portion of the Southwest, where it is considered a major pest of livestock. It attacks cattle, horses, sheep, goats, deer, and occasionally man. The immature stages of the tick attach in the ears. When fully fed the nymph drops to the soil and molts to the adult stage.
One of the most serious oonsequenoes to livestock caused by the ear tick is that it predisposes animals to sorewworm attack. Animals infested with the tick attempt to relieve themselves by scratching their ears. This results in laceration of the ears whioh, together with the occasional crushing of engorged nymphs, invites oviposition by the sorewworm fly. If animals, especially sheep, are not given prompt attention following screwworm infestation in the ear, they soon die.
As the result of studies conducted in the vicinity of klenard, Tex., a now method has been developed for controlling this tick. The experiments leading to this method and directions for treating livestock are given herein.
Distribution of Ear Ticks in Pastures
To learn the distribution of ear ticks in pastures, samples of soil and debris in and around places frequented by animals were collected and examined. For this purpose a No. 2 washtubful of material was considered a sample. The samples were examined by washing the soil and debris through a screen. Twenty-six samples from 10 different types of locations were examined. A sample of soil and debris from under the salt trough yielded several hundred ticks. The debris from under feed troughs was examined also but only an occasional tick was found. In all other locations only 5 ticks were found, 3 in samples
from a goat shed and 2 from the bed ground.
In view of these results, samples of debris from under salt troughs from widely scattered localities were examined and found to contain from a few hundred to more than 2,,000 ticks per trough. This conoentration of ticks indicated a possibility of controlling the parasite by the treatment of salt troughs with a material which would kill the ticks.
Experimental Treatment of Salt Troughs
A series of tests for killing ticks under salt troughs was conducted using a large number of materials. A mixture of equal parts of kerosene and used lubricating oil was found to be highly effective against all stages of the tick. This material also had the advantage of not being repellent to livestock.
Another test was conducted to learn whether this material would be generally satisfactory for the control of the ear tick. The ticks were removed from all the cattle in a pasture by means of an ear spoon. The troughs and the areas under them were sprayed once a month from April to October. It was found that the kerosene-lubrieating oil mixture penetrated the debris and soil and killed all ticks in the sprayed area. At the start of the test the animals had an average of 7 ticks per animal while at the close of the test they had an average of 3.1 ticks per animal. The test showed that some control was affected but that the treatment was not adequate by itself.
Experimental Treatment of Ears of Cattle
Tests with various chemical mixtures over a series of years had demonstrated that a mixture of pyridine and an adhesive, designated as stock 1029 (see page 4), gave outstanding results in killing the ear tick and in protecting animals from reinfestation, In two tests using 112 head of cattle the ears were treated with stock 1029 in April at which time there were on an average 7.2 ticks per animal. These cattle were examined 1 mouth later, at which time they had an average of 0.6 tick per animal. No additional treatments were made, but the cattle were examined each month for 4 months. At no time did the average number of ticks per animal exceed 0.72, and at the and of the 4 months the average was 0.5 tick per animal.
From 20 check animals kept in the same pastures the ticks were removed by means of an ear spoon and no treatment was made to the ears. At the beginning of the tests these animals had an average of 7.3 ticks per animal. One month later they showed an average of 6.6 tick's per animal. The ticks were again removed and at the end of a month the animals had an average of 8.0 ticks per animal. At the end of the tests the check animals had an average of 5.7 ticks per animal.
Combination Treatment of Ears and Salt Troughs
An experiment was oonduoted for the purpose of learning whether combination of the treatment to the ears of cattle and a treatmiat of the salt troughs would give better control than either treating alone.
Three pastures were selected for this work. In each pasture there were 42 head of cattle. The ears of the cattle in one pasture were treated with stock 1029, no treatment being made to the salt troughs* In another pasture the ticks were reoved from the oars of the cattle and the salt troughs were treated with a mixture of kerosene and used lubricating oil. In a third pasture the ears of the cattle were treated with stock 1029 and the salt troughs with the kerosenelubricating oil mixture. The results of this test are shown in table 1.
Table 1.- Comparative effectiveness of three types of treatments for the control of the ear tick
averagee -...er of Eticks p.r anf Treatment : May 26 June 30: July 28 Aug. 28 Sept. 22
Ears treated with stock 1029 5.3 0.6 0.72 0.72 0.52
Ticks removed from ears and
salt troughs treated with
kerosene-lubrioating oil 9.0 6.6 8.0 4.1 3,3
Ears treated with stock 1029
and troughs treated with
kerosene-lubricating oil 9.0 0.25 0.15 0.05 0.05
These data show that the combination treatment produced much better
results than either treatment used alone.
Pasture Clean-up Experiment
An experiment was begun in October 1944 to learn whether the ear tick population could be reduced or eliminated in a pasture where sheep, goats, and cattle are kept by treating the ears of the cattle with stock 1029 and spraying the salt trou&hs and areas under them with a mixture of equal parts of kerosene and used lubricating oil. A heavily infested pasture was selected for this test. Two hundred head of sheep, 20 goats, and 33 head of cattle were kept in the pasture throughout the test. The ears of the cattle were treated
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each month with stock 1029, and the salt troughs and the areas under them wore sprayed with equal parts of keraone and used lubricating oil. The ears of the sheep and goats were not treated.
At the beginning of the test the cattl, had an average of 9.1 ticks per ear. The treatment reduced the Infestation and kept it at a small fraction of a tick per ear. On May 11, 1945v a cow bioun to be highly susceptible to ticks was placed in the pasture after all ticks had been removed from her ears. On June 8 this cow had one tick in one ear aud none in the other. The tick was removed and the untreated cow was left in the pasture. She was examined each month for 5 months and at no time were any ticks found in her ears. An examination of the sheep and goats in October 1945 showed no ticks in their ears.
Composition and Preparation of Stock 1029
Stook 1029 is a mixture of pyridine in an adhesive containing 45 percent of rosin, 40 percent of Heroolyn (hydrogenated methyl, abietate), and 15 percent of dibutyl phthalate. The adhesive (called adhesive A58) is prepared by slowly heating the rosin, Heroolyn, and dibutyl phthalate, being careful to keep the mass well 'stirred until the rosin is liquefied. The mixture should not be overheated. An soon as the rosin is thoroughly liquefied, the heat should be removed and the mixture allowed to cool. When the adhesive is almost cool* 10 percent of pyridine (practical grade) should be added and the mixture stirred until uniformly mixed. Stirring should be done out of doors or in a well-ventilated'roa. Pyridine is inflammable and should be kept away from open flame.
Method of Treating Animals with Stock 1029
Stock 1029 should be applied to the ears of livestock by mans of a 1-inch paint brush. A brushful of the mixture should be inserted well down into the outer ear and rubbed about enough to insure a complete coverage of the deep convolutions and the inner surface of the outer ear. Animals may be treated in an open chute, but it is more convenient to use a stanchion er dehorning chute where the animal's head can be held more or less rigid. One gallon of stock 1029 will treat approximately 125 head of cattle.
Schedule of Treatments for Control of Ear Tick
Repeated field tests with several hundred head of cattle have demonstrated that the ear tick can be controlled by using the following plan of treatment. The ears of all cattle should be treated with stock 1029 at the time of the spring and fall round-ups. The salt troughs and the areas under them should be sprayed thoroughly or sprinkled with a mixture of equal parts of kerosene and used-lubricating oil. For the average 8-foot trough 2 or 2j gallons of the mixture should be used.* The troughs should be treated at monthly intervals throughout the year.