UNITED STATES DHAPTMET OF AGRICUL!URE
Agricultural Research Administration
Bureau of Entomology and Plant Quiarantine
A NEW Ra!EDY FOR FLEECE WORMS
By C. S. Rude, C. L. Smith, and H. E. Parish, Division of Insects Affecting Man and Animals
The true fleece worm, or wool ma~got, is the larva of the
blowfly Phormia regina (Meig.). Several other species at times initiate similar attacks on sheep and goats. In this report the term "fleece worm" has been expanded to include Cochliomyia macellaria (F.).
The fleece worms are among the most important blowflies attacking sheep, not only in the Western States, but also in many other parts of the world where sheen are produced extensively. They rank next to the scre~worm (Coebliomyia americana C. and P.) in infesting wounds of animals. However, the greatest injury is caused by their attacking the soiled wool, particularly before shearing in the spring, when the animals are carrying a heavy fleece and are inclined to scour. Sheep infested with fleece worms have a tendency to "fever" quickly, and unless animals receive nrcrot attention, they will not urvive. This condition is due in part to the rapidity with which the fleece worm infestation Noreads over the animal.
To prevent infestation of their animals, eqrecially of ewes at
lambing time, most sheenmen practice "crutching" or "teging," which consists of shearing the wool from the crutch late in the dvinter shortly before lambing begins and before green grass and weeds become abundant. In site of benefits gained by this practice many sheep become infested with fleece worms. This is rarticularly true when considerable rainfall occurs in the -nring and when the weather in general is cloudy, warm, and humid. Such weather prevents the wool from drying and thereby makes is more attractive to the
flies for egg deposition.
Various materials have been used for treating animals infested with fleece worms. In the case of sheen it has been nececspry to shear the infested area prior to treating, which is an expensive and disagreeable task. Research by the Bureau of Entomology,, and Plant Quarantine has developed a remedy which may be allied without shearing the infested areas. A preliminary report on this work was published by Knipling in 1942 1/. This remedy nenetrates the wool an( kills the larvae as it comes in contact with them, and at the sae time cots
I/ Knipling, E. F. A preliminary report on a treatment for fle ce worm-infestations in sheep. Jour. Fcon. Ent. T: <% <. 16.
WI I UNIV RSITY OF FLORIDA
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the wool and skin to give protection against subsequent reinfestation.
In developing this remedy a number of protective chemicals were tested which gave almost equally good results, but the one selected was chosen on the basis of safety, availability, and price, as well
The remedy consists of a proper mixture of benzene as a killer, diphenyl as a protective chemical, Triton 770 (sodium salt of an alkylthenoxypolyether sulfate) as a wetting agent, and n-butyl alcohol as a combining agent.
Preparation of the Remedy
The remedy is known as Formula M. S. 793F, and is composed of the following ingredients (Dro1nortions are by weight): Diphenyl, 10 parts; benzene, 8h parts; Triton 770, 1 part; n-butyl alcohol,
5 parts. The dinhenyl should be dissolved in the benzene, preferably by allowing the two substances to stand together in a closed container. Shaking the container will hasten the procedure. In no event should the mixture be heated over, or brought near, an open flame, as benzene is highly inflammable. The Triton 770 and the n-butyl alcohol should be mixed together, then added to the mixture of benzene and diphenyl, and thoroughly agitated by shaking. When first made the mixture will have a cloudy a-rrearance, which will disar)ear on standing. The finished -roduct is clear and almost colorless.
Use of the Remedy
In treating a sheep infested with fleece worms the extent of the infested area should first be determined. Sufficient of the remedy should then be poured onto the area to wet the wool, not only in the infested area but also for about 2 inches beyond. It is best to treat the outer portion of the infested area first to prevent worms from crawling into the uninfested wool. It is not necessary to rub or otherwise work the mixture in, as it penetrates the wool readily. The liulid may be poured from a bottle or small-mouthed can. Whatever container is used, it should be of a type that can be tightly closed when not in use. Apnroximately a pint of the liquid is needed to treat the average cqse of fleece worms. However, if care is taken to wet thoroughly the infested area Rnd the bordering region, a single applica-, tion is usually sufficifnt to effect a cure. Additional aoplicatione of" the remedy should be made whenever the wound becomes reinfested.
Formula M. S. 791F is safe to use on livestock, since it has been testee in several hundred sheep with no ill effects. It kills fleece worms quickly and provides satisfactory Drotection from reinfestation. Moreover, wounds treated with this remedy heal quickly.