The vaccines we all use for EEE, WEE, VEE and West Nile aren’t 100% effective and - no matter how hard we try to keep horses in during peak mosquito times and eliminate nearby breeding sites - there’s no way to completely avoid mosquitoes. You also can’t count on feeding garlic, sulfur or cider vinegar to keep them away. Like it or not, you need to use repellents and contact insecticides.
Permethrin, which is approved as a topical repellent/insecticide for horses, is effective against mosquitoes. Fly sheets won’t protect a horse from mosquito bites, as the mosquitoes can bite right through most kinds of cloth. However, you can lightly spray the sheet with 0.5% permethrin on both sides, just enough to moisten the fabric and allow it to dry before applying.
In addition, exposed skin should be covered with permethrin spray, 0.1 to 0.2% concentration, which you can make by mixing 5 to 10 cc of a 10% permethrin product, like Permectin II, in a gallon of water. Available at American Livestock Supply (www.americanlivestocksupply.com, 800-321-0235) and PBS Animal Health (www.pbsanimalhealth.com, 800-321-0235). About $20/quart. Use 25 cc per gallon of water to make a solution for spraying sheets. Permethrin is not for sale in all states.
The biggest mistake people make with repellents is not covering all exposed skin. If you miss even a few small spots, the mosquitoes will find them, and they feed near areas of skin covered with a repellent.
Strong fans set to blow across doorways to barns provide good physical barriers. Mosquitoes won’t fly against a strong air current. Spray barn walls with a solution of 1.25 ounces of 10% permethrin in a gallon of water to keep mosquitoes out of stalls.