Extension Bulletin 1389 insect answers CONTROL OF SHEEP KEDS The sheep ked or sheep “tick,” Melophagus ovinus, Sheep keds that become dislodged do not usually pose is found on sheep in most sheep-raising areas of the a threat of reinfestation to other sheep. Dislodged keds world. In the United States it is most abundant in the only live about 4 days off their hosts. Spread is al- west. most entirely from sheep to sheep, although people (shearers, etc.) can help to spread them. Symptomology and Economics The ked is ticklike in appearance, about 1/4 inch long, The sheep ked is a pest only of domestic or mountain and reddish or gray-brown in color. It is unusual in sheep and goats. There are no alternate host animals not laying eggs. Eggs, produced singly, are retained and no free-living stages. in the uterus and hatch there. The young larva re- mains within the female ked, feeding from special Keds generally infest the neck, breast, shoulders, nutritive glands until it is fully developed. Only one belly, and thighs, and can be easily detected by part- develops at a time. When full development is reached, ing the wool. They pierce the skin and suck blood, each larva is expelled almost immediately, forming a causing irritation to the sheep and forcing them to puparium that attaches to the wool. scratch and bite at themselves. Scratching results in wool tags left on fence wires. Heavily infested animals may become weak and un- thrifty and show weight loss, anemia, wool staining, reduced resistance to disease, and a condition called “cockle.” Cockles are raised bumplike skin blemishes caused by ked bites. They reduce the value of the skin. Young animals are the most susceptible to ked infes- tation, because keds migrate to the lambs after ewes have been sheared. In some areas, up to 25% reduc- tion in fleece yields has been noted. Adult sheep ked. Description and Life History The puparium is barrel-shaped, dark reddish brown, and about 1/8 inch long. During warm months, the The sheep ked is frequently called a sheep tick, but is adults emerge from the puparium in about 3 weeks; a true insect rather than a tick. It represents a family about 6 weeks are required during cold months. of flies parasitic on such mammals as deer, goats, and sheep. There are species that prey on some birds. Female keds live for about 5 to 6 months during which time they may produce up to two dozen young at a The sheep ked spends its whole life cycle on the host. rate of about 1 every 7 days. COOPERATIVE EXTENSION Ked populations build up during the fall and early If you use liquid treatments, allow drying time be- winter months, begin to peak during the first of the fore evening. Do not spray animals when daytime year, then decline until early summer. The decline is temperatures are below 40˚F. associated with resistance of the sheep at this time. The blood flow to the outer skin layer is cut off, caus- Management Suggestions ing ked starvation. There is also cellular infiltration to sites of ked feeding, blocking the free flow of blood A. Small Farm Flocks. Sheep keds can be easily con- to the parasite. trolled in small farm flocks by attaching a dust bag in a barn opening used by the flock. Close other barn Control accesses to force usage of the dust bag by the sheep as they enter and exit. Several insecticides registered for control of sheep keds on sheep are listed in this publication. Diazinon Dust bags should contain a recommended pesticide and permethrins are both labeled for low pressure and may be a commercial product or simply made spray (knapsack sprayer) and sprinkling can applica- from two burlap bags placed one inside the other. tions. These work well for small flock owners. A Hang dust bag at the height of the animal’s shoulder. number of other products, particularly for commer- When treating just a few sheep, hand sprinkling or cial operators, are listed in the PNW Insect Control hand dusting are probably the most convenient meth- Handbook available in Cooperative Extension county ods of control. offices. Sheep can be sprayed, sprinkled, dipped, or dusted. (Goat treatments are included.) The best time B. Commercial Flocks. Large commercial flocks can to treat sheep is in spring, after shearing, when the be treated for infestations most economically by dip- wool is short and shear cuts have healed. Sheep ping or spraying after shearing, and spraying again sprayed during cold weather are more subject to stress. in the fall. By Art Antonelli, Ph.D., Washington State University Cooperative Extension entomologist, WSU Puyallup; and Larry Sandvol, Ph.D., University of Idaho Cooperative Extension System entomologist, Univ. Idaho, Aberdeen. COOPERATIVE EXTENSION College of Agriculture and Home Economics Use pesticides with care. Apply them only to plants, animals, or sites listed on the label. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock. Copyright 1999 Washington State University WSU Cooperative Extension bulletins contain material written and produced for public distribution. You may reprint written material, provided you do not use it to endorse a commercial product. Alternate formats of our educational materials are available upon request for persons with disabilities. Please contact the Information Department, College of Agriculture and Home Economics, Washington State University for more information. You may order copies of this and other publications from the WSU Bulletin office, 1-800-723-1763, or online http://caheinfo.wsu.edu Issued by Washington State University Cooperative Extension and the U.S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. Evidence of noncom- pliance may be reported through your local Cooperative Extension office. Trade names have been used to simplify information; no endorsement is intended. Revised September 1999. A Subject codes 180, 352 EB1389.