Agriculture and Natural Resources Livestock Insect Series Horse Flies and Deer Flies on Cattle Dr. Donald R. Johnson More than 300 Life History Extension Entomologist species of horse flies and deer flies (family Eggs are Dr. Gus Lorenz Tabanidae) have been deposited in Extension Entomologist - recorded in North masses of up to IPM Coordinator America. More than 1,000 on vegeta­ 50 species of horse tion growing in or flies and deer flies overhanging Glenn Studebaker have been identified streams, ponds or Extension Entomologist in Arkansas. In some Black Horse Fly, Tabanus spp. swampy areas. Arkansas localities, Eggs usually Dr. John D. Hopkins the horse fly season hatch in about 4 Assistant Specialist - begins in early April to 7 days. Larvae quickly drop to the Entomology and and does not end surface of the Insecticide Testing until frost in the fall. Coordinator water or moist soil and quickly Horse flies and burrow into the deer flies are robust, mud, damp earth measuring in length or decaying Deer Fly, Chrysops spp. from approximately matter. They feed 1/3 inch for the on organic matter smaller species to 3/4 or 1 1/2 inches and other animal life. Larvae may for the larger ones. They are various take one to two years to develop. colors but are usually gray, splattered Mature larvae measure up to about with brown or black. Both kinds are 2 inches in some species, are tapered strong fliers. Only the females suck at both ends and have a fleshy ring on blood, and they are vicious biters. The each body segment. After reaching males feed on nectar and are of no maturity, the larvae pupate, and the adult emerges one to two weeks later. consequence as animal pests. These flies are the most annoying of live­ stock pests. Nature of Damage Female flies obtain blood meals Female horse flies and deer flies from a wide variety of warm- and have broad, flat, blade-like mouth­ parts that cause a large, deep and cold-blooded animals, particularly painful wound. The painful bite and Arkansas Is cattle, horses and deer. Although these buzzing sound the flies make while Our Campus flies often attack man and can inflict flying around animals may cause painful bites, humans are not their them to stop grazing and cluster primary hosts. Deer flies more together for protection. This activity Visit our web site at: commonly attack man than do causes weight loss and reduced milk https://www.uaex.uada.edu horse flies. University of Arkansas, United States Department of Agriculture, and County Governments Cooperating flow, and the clustered animals often injure each Several factors have been suggested to explain other by hooking or kicking while they are close the difficulties of controlling horse flies in field situa­ together for protection. Weight loss estimates have tions where it is not feasible to handle the animals on been as high as 100 pounds per animal during the a frequent schedule. Some of these factors are: (1) the season, and estimates on reducing milk flow have relatively large size of the flies, which increases the been 20 to 30 percent. dose of insecticide necessary to produce mortality, (2) the brief feeding period on the animal when it would Another important factor is the blood loss. In six be in contact with a treatment on the animal, (3) the hours, 20 to 30 flies can take almost a third of a pint continued emergence and host seeking of females of of blood. Other estimates have been as high as a third numerous species over a relatively long period, (4) the of a quart where infestations were slightly higher. These estimates do not include the large drop of blood ability to fly from emergence sites that may be a that is usually left at the side of each bite. considerable distance from the host to be protected and (5) the wide range of larval habitat which Their intermittent feeding makes them ideal for precludes, except in limited situations, larval control. the mechanical transmission of disease-causing pathogens. A fly interrupted during its feeding may Some degree of repellency can be obtained for two pass readily to another animal so that both sick and or three days after applying a spray mixture of healthy animals may be fed on in succession by the pyrethrins and piperonyl butoxide. Use of this same fly. Anaplasmosis, anthrax, tularemia and mixture may benefit dairymen or small herd owners several other diseases are known to be spread by in areas of heavy local infestation. these vicious bloodsuckers. Insecticides currently registered on cattle only Control afford moderate control of horse flies at best. Spray the entire body of the animal, paying particular Control of horse flies and deer flies is very attention to the areas most frequented by the horse difficult. Insecticides are usually ineffective since the flies. Frequent treatment may be necessary. Your insects spend little time on the animals. Insecticide county Extension agent has information concerning treatment of breeding areas is also impractical. which insecticides to use. DR. DONALD R. JOHNSON, Extension entomologist, and Issued in furtherance of Cooperative Extension work, Acts of May 8 and DR. GUS LORENZ, Extension entomologist - IPM coordinator, are June 30, 1914, in cooperation with the U.S. Department of Agriculture, with the Cooperative Extension Service, University of Arkansas, Director, Cooperative Extension Service, University of Arkansas. The Little Rock. GLENN STUDEBAKER, Extension Arkansas Cooperative Extension Service offers its programs to all eligible entomologist, is located at the Northeast Research and Extension persons regardless of race, color, national origin, religion, gender, age, Center, Keiser. DR. JOHN D. HOPKINS is assistant specialist ­ disability, marital or veteran status, or any other legally protected status, entomology and insecticide testing coordinator, Cooperative and is an Equal Opportunity Employer. Extension Service, University of Arkansas, Lonoke Agricultural Center, Lonoke. FSA7035-PD-4-01RV .