This fact sheet was developed by students enrolled in Purdue's ANSC 442 Sheep Management course in Spring 2003, as a semester project. These fact sheets provide useful information on various topics related to sheep. View the list of fact sheets.
What is Sheep Ked?
Melophagus ovinus, sheep ked, is a brown, hairy fly that resembles the look of a tick. This wingless fly is about 4 to 6 mm long and has a small head that is broad. The legs of the sheep ked are very strong and are tipped with claws. Sheep ked lives their whole lives in the wool of sheep. The areas of the sheep that sheep ked are most commonly found on are the neck, shoulders and stomach. If removed form the sheep, the adult females only live for 7-10 days.
Sheep ked only lives for about four to six months. Within this time they produce anywhere from 10-20 larvae. When the larva is deposited on the wool of the sheep they are attached with a glue-like material. The larva immediately hardens and becomes a darker color when forming a puparium, which will contain the pupa a few days following. This pupa stage lasts for 19-23 days in the summer and 20-36 days in the winter. During this time the sheep ked is not susceptible to insecticides. This means the dip process is not effective at this time on this stage of the sheep ked.
Why Is The Sheep Ked A Problem?
Since the sheep ked is a blood sucking insect, naturally it causes irritation to the host, resulting in many different damages that are economical losses.
In young lambs the sheep ked my cause anemia and retard weight gain. Since the sheep ked sucks the blood from its host it causes irritation to the sheep's hide causing it to rub resulting in loss and damage of the wool. When the sheep ked bites and scratches the sheep, it makes firm, hard nodules that develop on the top layer of the skin called "cockle", which reduces the value of the hide, because of the decline in the tinsel of the leather. Because of the decline in the sheep's immune system due to the feeding of the ked, the wool production suffers as well. The ked feces also stain the sheep's wool making it very difficult to wash out; therefore the best way to get rid of the feces is to shear the wool. Also, when the ked and its pupae are found in the harvested wool, it gives the wool a "dirty classification" resulting in a decrease in value there as well.
The physical appearance of the sheep also decline due to the heavy infestation of sheep ked making the sheep itch causing theme to have a dirty and ratty appearance. This insect causes many problems to the sheep flock that result in an economic loss. A few things that the sheep ked causes which result in economic loss is a two pound reduction in carcass weight, twenty percent decline in clean dry weight of wool and a seven percent loss in clean fiber.
Sheep Ked Control and Prevention
Signs of Infestation
Sheep Keds are found year-round in sheep wool and can be visually detected by parting the wool. Keds infest the neck, breast, shoulders, flank and rump in the greatest numbers, but tend not to feed on the back where the most debris collects in the wool.
Blood-feeding and the ked's resulting excrement permanently stain the wool. Sheep will bite, scratch and rub due to the irritation produced the ked's feeding, thereby damaging the wool and causes the fleece to become thin, ragged and dirty.
How to Rid Sheep of Keds
The simple act of spring shearing reduces ked populations up to 75% by removing pupa and adults. Wool should, however, be promptly removed from the property to prevent re-infestation. While keds can crawl onto new hosts, this is not a major method of infestation because they will only live around 4 days off the host. The main way sheep are infested is from contact with other infested sheep. For this reason ewes should be shorn prior to lambing.
Insecticidal treatment after shearing is common and the most effective control method. Pupated larvae are not often affected by chemicals, so choosing a long-acting product to kill these keds after they emerge offers the best control. Treatments typically cost less than 10 cents per sheep with a 99.5% to 100% efficacy rate. It has been found that products containing pyrethroids are very effective against Sheep Keds.
Methods of Chemical Application
The best method of control application depends upon flock size, facilities, and labor. Products are available in spray, dip, pour-on, and dust applications. With pour-on application, it may be best to wait until sufficient wool growth after shearing is present in order for the wool to retain the liquid formulation well. Sheep sprayed during cold weather are likely to experience more stress and therefore should not be sprayed if daytime temperatures are not above 40°F. Any liquid treatments should be done with a sufficient amount of time left for drying before nightfall. Consult the links below for more information on what control method may be best for your farm situation along with information and recommendations on approved chemicals.
** All labels on chemicals should be read prior to use and followed for best results. Ensure that sheep are not treated too close to slaughter or during lactation as per label instructions. **
The institution of ked-free programs began with Wyoming and has since been established in several surrounding states. Upon recognizing the major impact sheep ked can have economically on sheep production and how easily the problem could be managed the Cooperative Extension Service at the University of Wyoming along with the Wyoming Wool Growers Association began a program to establish Wyoming as the first ked-free state.
Currently the programs in participating states work by inspecting all sheep for keds and treating them at shearing time. Any replacements or breeding stock are also treated before addition to a flock. Sheep from these programs are then certified as ked-free when subsequently sold or marketed.
Print resource (source of photos and thorough information) - Photos are
Mullen, Gary, and Lance Durden, eds. Medical and Veterinary Entomology. Boston, New York, San Diego, and San Francisco: Academic Press: An Imprint of Elsevier Science. 2002. Chapter 17: Louse Flies, Keds, and Related Flies (Hippoboscoidea).
Merck Veterinary Manual: complete information on Sheep Ked with photos
Sheep Insect Management
Merial - Disease Information
Kansas State University Research and Extension - Sheep Ked
Agriculture and Agri-Food Canada
Other Links for More Information
Links with chemical information:
http://184.108.40.206/search?q=cache:yTAy3aJ9vFUC:www.entomology.cornell.edu/Extension/Vet/PDF_Files/2001%2520Pesticide%2520Recommendations/Sheep_Pesticide_Guide_2001.pdf+sheep+ked+chemical+control&hl=en&ie=UTF-8 (scroll down to pg 5)
Links with suggestions on application methods per farm type:
Links with information on Ked-free programs:
http://uwadmnweb.uwyo.edu/News/2002/march/uwnews19.htm (scroll down to CONTROLLING THOSE SHEEP TICKS)