Livestock Insects–Sheep and Goats

Sheep Keds

John B. Campbell

Identification and Field Biology

Sheep keds are wingless flies that resemble ticks. Keds spend their entire life cycle on sheep, transferring to lambs by animal contact. The female deposits a fully-developed larva on a wool strand. A red puparium (case) forms around the larva. A fully-developed sheep ked emerges from the puparium after about 21 days. Sheep keds feed on the blood of sheep. Numbers increase in the winter and decline in the summer.

Animal Behavior and Economic Losses

Sheep keds have been reported to cause a 2 lb. reduction in carcass weight, a 20% reduction in clean, dry weight of fleece and a 7% loss in clean fiber. Heavily-infested sheep itch and have a dirty unthrifty appearance. The feeding by the ked causes firm, hard nodules to develop in the grain layer of the sheepskin. This causes a defect in the skin known as “Cockle”, which reduces the value of the skin because of a decrease in tinsel strength of the leather.

Management Strategies

Chemical

Several insecticides are available, which provide good control of sheep ked. Perhaps the best time to treat sheep for keds is right after shearing. If lambs are infested, they should be treated also, and any replacement animals should be treated before they are brought into the flock. Wyoming and North Dakota, and perhaps other western sheep producing states have a ked free program so that feeder lamb buyers know the lambs are ked free. There are several methods of application, which provide satisfactory control. The insecticides approved for control of ectoparasites of sheep are listed at the end of this chapter.

Categories: Livestock insects, Sheep, Goats, Sheep keds

Date: 12/17/2002