NMSU: 1994 Guide for Control of External Parasites of Sheep and Goats
NMSU branding

1994 Guide for Control of External Parasites of Sheep and Goats

Guide B-112

L.M. English, Extension Entomologist

College of Agricultural, Consumer and Environmental Sciences New Mexico State University

This Publication is scheduled to be updated and reissued 7/99.

Note: Any insecticide preceded by "RU" (Restricted Use) means all or some uses of this product have been restricted by EPA. Any applicator must be certified and licensed before buying restricted-use products.

General Precautions

DO NOT spray animals in a confined, nonventilated area.

DO NOT dip animals when thirsty or overheated. Water animals well before treatment so they will not drink the vat fluid.

DO NOT contaminate feed or drinking water.

DO NOT apply insecticides to sick animals or animals under stress.

DO NOT apply insecticides to lambs less than 3 months old, and use light applications on lambs 3 to 6 months old.

DO NOT treat animals with coumaphos 10 days before or after shipping or weaning, or after exposure to contagious or infectious diseases.

DO NOT apply coumaphos, dioxathion, or ronnel to animals in conjunction with oral drenches or with internal medications such as phenothiazine, or with natural or synthetic pyrethroids or their synergists, or with other organo phosphates.

DO NOT use coumaphos, dioxathion, or ronnel on lactating milk goats.

Fleeceworms (Wool Maggots)

Docked and tagged sheep are not usually bothered with fleeceworms.

Even in well-managed flocks, fleeceworms sometimes become a problem during a long stretch of cool, damp weather. Spraying the rear ends of the sheep is a good control and preventive measure under such conditions. High-pressure sprays (150-250 lb pressure) are best; however, if a low-pressure sprayer (50-150 lb pressure) is used, be sure to add 1-2 lb of household detergent per 100 gallons of water. For control, see table 1.

Coumaphos (Co-Ral). Use a 0.125% solution made by mixing 4 lb of 25% Co-Ral wettable powder in 100 gal of water, or 2 oz in 3 gal of water.

(RU) Dioxathion (Delnav). Use a 0.15% solution made by mixing 2 qt 30% Delnav livestock emulsifiable concentrate in 100 gal of water, or 4 tsp in 1 gal of water.

Ronnel (Korlan). Use 2.5% ronnel livestock bomb. Spray infested area and a 3-inch band around the margin.

Restrictions: Coumaphos requires a 15-day preslaughter interval. No preslaughter is required for dioxathion or ronnel; however, DO NOT use dioxathion more than once every 2 weeks.

Table 1. Controls for wool maggots.

Pest Insecticide Dosage [Amt. of insecticide per 100 gallons as spray or use as indicated] Remarks [Interval between application and slaughter]
Wool maggots  
Co-Ral spray4 lb 25% WP (sheep and goats) Do not apply within 15 days of slaughter. Do not use within 14 days of freshening of dairy goats.
Lindane aerosol Apply locally as fleeceworm treatment Follow manufacturer's recommendations.
Permethrin spray, paint, or dip Use 1 lb of 25 WP to 60 gal water. Do not use on goats. Do not use within 14 days of slaughter. ID. 24(c).
Permethrin spray, paint, or dip Use 1 lb 25 WP to 60 gal water. Spray affected areas or entire body or bedding. Re-treat after 4-6 weeks if needed. Remove feed and water. Do not treat more often than every 14 days.
Chlorpyrifos aerosol Apply locally as fleeceworm treatment. Treat at 5-7 day intervals until would heals.
Dioxathion Use 0.5 gal of 20% EC as spray or dip. Treat as necessary but not more often than every 2 weeks.

Sheep Scab or Scabies

Psoroptic scabies is thought to be eradicated in domestic sheep in the United States. Any sheep or goat suspected of being scabies infected should be quarantined. Consult with your county agent or local veterinarian concerning regulations for treating and shipping as established by New Mexico law.

New Mexico has a Scabies Control and Eradication Law, administered and supervised by the state veterinarian of New Mexico Department of Agriculture and accredited and approved by veterinarians throughout the state.

Sheep Lice

Lice will not be a problem in flocks sprayed or dipped regularly to control sheep ticks. Be sure all replacement ewes and rams are treated before they are added to the flock. For controls, see table 2.

Table 2. Controls for sheep lice.

Pest Insecticide Dosage [Amt. of insecticide per 100 gallons as spray or use as indicated] Remarks [Interval between application and slaughter]
Lice  
malathion spray 16 lb 25% WP OR 1 gal 57% EC No time limitation between application and slaughter. Do not apply to dairy goats. Do not treat animals under 1 mo.old.
diazinon spray0.5 lb 50% WP (sheep only) Do not apply within 14 days of slaughter. Do not use on goats.
Co-Ral spray or dip 2 lb 25% WP (sheep and goats)Do not apply within 15 days of slaughter. Do not use on lactating dairy goats. Do not use within 14 days of freshening of dairy goats.
Methoxychlor sprayUse 8 lb 50% WP OR 2 gal 25% EC. Spray to insure thorough coverage. Use 2 qt spray solution per animal. No time limitation. Do not use on lactating diary goats.
Ciodrin Mix 1 pt 21.5% EC in 10 gal water or 2.5 pt 13% EC in 15 gal water. Spray animal thoroughly using up to 1 gal for large animals. Repeat application in 14 days.
Ciovap spray Use 2 gal 12% EC. Spray animals thoroughly using up to 1 gal per animal. Apply a second application in 10 to 14 days.Repeat as necessary but not more often than once every 7 days. No time limitation between application and slaughter.
Fenvalerate spray or pour-onMix 1 pt 10% WDL in 50 gal water. Wet animal with up to 1 qt dilute spray or mix 1 pt in 6 1/4 gal water. Pour up to 4 oz down backline of animal. For pour-on mixtures add 2 fl oz wetting agent per 5 gal water.Repeat application in 30 days if necessary. Do not treat more than twice in the spring and fall. Do not apply within 2 days of slaughter.
Fenvalerate spray or pour-on Mix 1 qt 10 WDL in 1 gal water. Use 1/3 oz of dilution per animal.Repeat in 30 days if necessary. Do not use more than twice in the spring and fall. Do not apply within 2 days of slaughter. Do not use on lactating goats.
Dioxathion - 0.15% spray or dip Use 1/2 gal 27.5% EC OR 1 gal 15% EC. Do not use on dairy animals. Do not use more often than every 2 weeks. No time limitation between application and slaughter.
Permethrin 0.05% spray Mix 1 lb 25 WP to 60 gal water. Spray affected areas or entire body or bedding. Retreat after 4-6 weeks if needed. Remove feed and water. Do not treat more often than every 14 days.
Permethrin 1% pour-on Use 1/4 fl oz per 50 lb body wt up to 3 fl oz per animal.
Permethrin Use 1 pt 11% EC in 25 gal water. Use 1-2 qt spray on animal.
Permethrin 1% pour-on. Pour along backline and down face. Use 1/2 oz per 100 lb of body weight to a maximum of 5 oz per animal. (Sheep only).Repeat as needed. Use no more than once every 2 weeks.

Sheep Tick or Ked

When and how to use:

Treatment for sheep ked is easily applied and is often the most effective following spring shearing. Sheep ked should, however, be controlled any time significant numbers are found.

When heavily infested ewes are shorn, the ticks will move to lambs that are still nursing. Consequently, treat lambs when the ewes are treated, but spray lightly and use EXTREME CAUTION when treating lambs under 3 months of age. DO NOT treat animals under 3 months of age with coumaphos under any circumstances.

Spraying or dipping once a year will usually keep sheep ticks under control. Be sure to treat all bucks and replacement ewes before adding them to the flock.

Dipping does a more thorough job than spraying, but spraying can provide good control.

High-pressure sprayers are more convenient and usually more effective when large flocks are treated. An adequate job can be done with low-pressure sprayers (40 to 100 pounds) if 1 to 2 pounds of household detergent is added to each 100 gallons of water. For controls, see table 3.

Table 3. Controls for sheep tick or ked.

Pest Insecticide Dosage [Amt. of insecticide per 100 gallons as spray or use as indicated] Remarks [Interval between application and slaughter]
Sheep tick or ked  
  Lindane spray Use 1.5 lb of 25% WP. Spray along back and around ears, spraying against wool. Do not treat within 30 days of slaughter. Do not use on dairy goats. Do not use on thirsty, overheated, sick animals, or animals under 3 mos. of age.
Diazinon spray 0.5 lb 50% WPDo not treat within 14 days of slaughter. Do not use on goats.
Co-Ral spray or dip 4 lb 25% WP (sheep and goats)Do not apply within 15 days of slaughter. Do not use on lactating dairy goats. Do not use within 14 days of freshening of dairy goats.
Fenvalerate spray or pour-on Mix 1 pt 10% EC in 50 gal water. Wet animal with up to 1 qt dilute spray or mix 1 pt in 6 1/4 gal water. Pour up to 4 oz down backline of animal. For pour-on mixtures add 2 fl oz wetting agent per 5 gal water. Repeat application in 30 days if necessary. Do not treat more than twice in the spring and fall. Do not apply within 2 days of slaughter on goats.
Malathion spray 16 lb 25% WP, OR 1 gal 57% EC No time limitation between application and slaughter. Do not apply to dairy goats. Do not treat animals under 1 mo. old.
Permethrin1% pour-on. Pour along backline and down face. Use 1/2 oz per 100 lb of body weight to a maximum of 5 oz per animal (sheep only). Repeat as needed. Use no more than once every 2 weeks.
Dioxathion spray or dipUse 1/2 gal 27.5% ECOR 1 gal 15% EC. Do not use on dairy animals. Do not use more often than once every 2 weeks. No time limitation between application and slaughter.

Secondary Screwworms

Use 5% coumaphos (Co-Ral) dust or 2.5% ronnel (Korlan) livestock bomb as described earlier for fleece worms.

No preslaughter interval is required with 5% coumaphos dust or 2.5% ronnel livestock bomb when used as a spot treatment.


New Mexico State University is an equal opportunity/affirmative action employer and educator. NMSU and the U.S. Department of Agriculture cooperating.

Reprinted July 1994
Electronic Distribution January 2001