E-695 July 1946 United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine CONTROL OF THE EAR TICK By C. S. Rude and H. E. Parish Division of Inseots* Affecting Man and Animals The ear tick (Ornithodoros megninl Duges) is widely distributed in the United States , Mexico, and central 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 livestook. It attaoks cattle, horses, sheep, goats, deer, and occasionally man* The immature stages of the tiok attach in the ears* When fully fed the nymph drops to the soil and molts to the adult stage* One of the most serious eonsequenoes to livestock caused by the ear tick is that it predisposes animals to sorewworn attack* Animals infested with the tick attempt to relieve themselves by scratching their ears. This results in laoeration of the ears whioh, together with the oooasional orushing of engorged nymphs, invites ovi position by the screwworm fly. If animal*, especially sheep, are not given prompt attention following screwworm infestation in the ear, they soon die. As the result of studies conduoted in the vicinity of Menard, Tex., a new 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 tioks in pastures, samples of soil and debris in and around places frequented by animals were colleoted 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 soreen. 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 tioks were found, 3 in samples from a goat shed and 2 from the bed ground. In view of those results, samples of debris from under salt troughs from widely scattered localities were examined and found to o on tain from a few hundred to more than 2,000 tioks per trough. This con- centration of tioks indioated a possibility of controlling the parasite by the treatment of salt troughs with a material which would kill the tioks. 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 lubrioating 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 tioks were removed from all the cattle in a pasture by means of an ear spoon. The troughs and the areas under them were sprayed onoe a month from April to October. It was found that the kerosene- lubri- oating 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 tioks per animal while at the close of the test they had an average of 3.1 tioks per animal. The test showed that some control was effeoted 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 tiok 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 month later, at which time they had an average of 0.6 tiok per animal. No additional treatments were made, but the oattle were examined each month for 4 months. At no time did the average number of tioks per animal exoeed 0.72, and at the end of the 4 months the average was 0.5 tiok per animal. From 20 cheok 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 tioks per animal. One month later they showed an average of 6.6 tioks per animal. The tioks were again removed and at the end of a month the animals had an average of 8.0 tioks per animal. At the end of the tests the check animals had an average of 5.7 tioks per animal. Combination Treatment of Ears and Salt Troughs In experiment mat eonduoted for the purpose of learning whether a combination of the treatment to the ears of oattle and a treatment of the salt troughs mould give better oontrol than either treatment alone. Three pastures were selected for this work. In eaoh pasture there mere 42 head of oattle. The ears of the oattle in one pasture mere treated with stook 1029, no treatment being made to the salt troughs. In another pasture the ticks were removed from the ears of the oattle and the salt troughs were treated with a mixture of kerosene and used lubrioating oil. In a third pasture the ears of the oattle were treated with stook 1029 and the salt troughs with the kerosene- lubrioating oil mixture. The results of this test are shown in table 1. Table 1.- Comparative effectiveness of three types of treatments for the oontrol of the ear tick i Average number of tioks per an£maT Treatment | May 26 : June 30* t t July 28 J Aug. 25 : Sept. 22 Ears treated with stook 1029 5.9 0.6 0.72 0.72 0.62 Tioks removed from ears and salt troughs treated with kerosene-lubricating oil 9.0 6.6 8.0 4.1 3.5 Ears treated with stock 1029 and troughs treated with kerosene- lubrioating oil 9.0 0.26 0.15 0.05 0.05 These data show that the combination treatment produoed muoh better results than either treatment used alone. Pasture Clean-up Experiment An experiment was begun in Ootober 1944 to learn whether the ear tiok population oould be reduoed or eliminated in a pasture where sheep, goats, and oattle are kept by treating the ears of the oattle with stook 1029 and spraying the salt troughs and areas under them with a mixture of equal parts of kerosene and used lubrioating oil. A heavily infested pasture was seleoted for this test. Two hundred head of sheep, 20 goats, and 33 head of oattle were kept in the pasture throughout the test. The ears of the oattle were treated UNIVERSITY OF FLORIDA IJIIIIIII - 4 - 3 1262 09238 7272 eaoh month with atook 1029, and the salt troughs and the areas under them were sprayed with equal parts of kerosene and used lubricating oil* The ears of the sheep and goats were not treated. At the beginning of the test the oattle had an average of 9.1 tioks per ear. The treatment reduoed the infestation and kept it at a small fraction of a tiok per ear. On May 11, 1946, a oow known to be highly susoeptible to tioks was plaoed in the pasture after all tioks had been removed from her ears. On June 8 this oow had one tiok in one ear and none in the other. The tiok was removed and the untreated oow was left in the pasture* She was examined each month for 5 months and at no time were any tioks found in her ears* in examination of the sheep and goats in October 1945 showed no tioks in their ears. Composition and Preparation of Stook 1029 Stook 1029 is a mixture of pyridine in an adhesive containing 45 peroent of rosin, 40 percent of Heroolyn (hydrogenated methyl abietate), and 15 peroent of dibutyl phthalate. The adhesive (oalled adhesive A58) is prepared by slowly heating the rosin, Heroolyn, and dibutyl phthalate, being oareful to keep the mass well stirred until the rosin is liquefied. The mixture should not be overheated. As 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 room. Pyridine is inflammable and should be kept away from open flame. Method of Treating Animals with Stook 1029 Stook 1029 should be applied to the ears of livestook by means of a 1-inoh paint brush. A brushful of the mixture should be inserted well down into the outer ear and rubbed about enough to insure a complete ooverage of the deep convolutions and the inner surfaoe of the outer ear. Animals may be treated in an open ohute, but it is more convenient to use a stanohion or dehorning chute where the animal 1 s head oan be held more or less rigid. One gallon of stook 1029 will treat approximately 126 head of oattle. Schedule of Treatments for Control of Ear Tiok Repeated field tests with several hundred head of oattle have demon- strated that the ear tiok can be oontrolled by using the following plan of treatment. The ears of all oattle should be treated with stook 1029 at the time of the spring and fall round-ups. The ealt troughs and the areas under them should be sprayed thoroughly or sprinkled with a mixture of equal parts of kerosene and used-lubrioating oil. For the average 8-foot trough 2 or 2& gallons of the mixture should be used. The troughs should be treated at monthly intervals throughout the year*