E-686 United States Department of Agriculture Agricultural Researoh Administration Bureau of Entomology and Plant Quarantine A NEW REMEDY FOR THE CONTROL OF THE GULF COAST TICK By C.S. Rude, Division of Inseots Affecting Man and Animals The Gulf Coast tiok ( Amblyomma maoulatum Koch) is a- serious enemy of livestook in the region bordering the Gulf of Mexico. In general it does not become sufficiently abundant to be of eoonomio importance more than 100 miles inland. Specimens have been examined from all the Gulf Coast States, from Georgia and South Carolina, and from Mexico. The tiok has also been reported from Central and South America. It is a three-host tiok,l/ the immature stages being found on birds and small mammals. The adults attack cattle, horses, sheep, goats, hogs, deer, and man. They generally attach to the outer ear of the host near the tip. Sometimes they attaoh to the eyelids or around the base of the horns. They are frequently found under the baok of the hump on Brahma bulls. On horses they often attack in the mane or foretop, where they produce troublesome sores. Nature of Injury When the tioks attaoh t6 the ear, they oause the ear to swell and exude a yellowish serum, which dries and forms a hard scab or orust. This soab may be as muoh as one-quarter inch thick and the ticks will be almost totally encased in it. In severe cases the ears beoome greatly swollen and oraok open. These oases usually result in per- manent malformation. By far the greatest loss, however, is from tiok injury causing the animals to be susceptible to attaok by screwworms. In some seasons fully 80 percent of the sorewworm cases, in areas where this tiok is abundant, are the direct result of tiok injury. Many animals die as the result of these attacks, but even greater loss is caused by the deorease in weight and impaired oondition of the livestock, and by the expenditure of time required to look after and treat the injured animals. In Texas the period of severe tiok injury usually starts in July and oontinues until about the middle of October. Pasture Mowing and Tick Control • Among some ranchmen in the coastal area there is a belief that systematic mowing of pastures to prevent rank growth of weeds and l/ Hixeon, H. Field biology and environmental relationships of the Gulf Coast tiok in southern Georgia. Jour. Econ. Ent. 33: 179-189. 1940. - 2 - coarse grass aids in the control of the Gulf Coast tick. Ho detailed studies have been conducted along this line, but observations were made that tend to bear out this belief. Airing the period 1942 to 1945 several pastures were observed in whioh a systematic program of mowing was carried out. The tick populations in these pastures were consis- tently low while in adjoining unmowed pastures the ticks were abundant. A typical example is the observation in 1944 of two pastures which were similar in every respect except that one had been mowed regularly for several years. On August 8 the cattle in the mowed pasture had an average of 0.47 tick per ear as compared with 4.5 per ear in the unmowed pasture. On September 20 the cattle in the mowed pasture had an average of 0.17 tick per ear in contrast to 5.1 ticks per ear in the unmowed pasture. Although such limited observations are not conclusive, they do indicate that systematic mowing of pastures may play an important role in the control of the Gulf Coast tick. Treatment for Ears of Cattle and Sheep Experiments were conducted from 1942 to 1945 for the purpose of developing a remedy that would kill the Gulf Coast tick on cattle and give a satisfactory period of protection from reinf estation. This work was made possible by the cooperation of a group of ranohmen in Jackson, Calhoun, and Matagorda Counties in Texas, These men furnished their herds and ranch facilities for the tests. A large number of animals were treated and a number of chemicals were tested. A mixture containing DDT in a nondrying adhesive gave the best results. Preliminary tests showed that a mixture containing 2 percent of DDT was not so effective as one in which the DDT content was 5 percent. Several adhesives were tested in the search for one possessing the desired properties. The remedy which was finally developed, and which gave consistently good results in extensive tests, has been designated as stock 1037. This remedy has not been tested throughout the entire area in the United States which is infested with the Gulf Coast tick. Experiments conducted in Texas indicate that it can be used successfully' in that region. The preparation is not recommended for application to any animals except cattle and sheep, Composition and Method of Preparing Stock 103_7.— This preparation contains 5 percent of technioal DDT, 47 percent of rosin, 33 percent of Hercolyn (hydrogenated methyl abietate), and 15 percent of dibutyl phthalate. All measurements are made by weight. - 3 - To prepare this stock, place the DDT and dibutyl phthalate to- gether and stir or shake until the LDT is in solution. Place the rosin and Hercolyn in another container and heat slowly until the rosin is completely liquefied. During the heating the mixture should be stirred frequently to prevent soorching. After the rosin is liquefied, remove the heat and allow the mixture to cool. When the temperature is down to 125°F. or less, add the dibutyl phthalate and DDT and stir until uniformly mixed. As soon as the mixture is cold, it is ready to use. Method of Using Stock 1037 on Cattle and Sheep . — From experiments conducted it appears that, when properly applied, stock 1037 will kill the Gulf Coast tick and prevent reinf estation for 3 to 6 weeks. For best results the mixture should be applied to the ears of cattle or sheep as soon as ticks begin to be numerous. A second application should be made when ticks again begin to attach to the animals . I'his will usually be in 3 to 6 weeks after the first treatment. The preparation should be applied liberally to both the inside and outside of the outer ear and around the base of the horns. It is best applied with the bare hands and should be well rubbed into the hair and skin. The material is not injurious to the hands and can be removed readily with benzene, white gasoline, or kerosene. The hands should then be washed immediately with soap and water. One gallon of stock will treat 125 to 150 head of cattle. UNIVERSITY OF FLORIDA 3 1262 09238 7587