Pest and fly control for horses
by Matt Mullen
All horse owners share the challenge of protecting their horses from pasture and stable flies. These insects aren’t just irritating—they can spread disease and feed on horses' blood, causing digestive problems and stunting the horse’s growth.
Understanding how various types of flies attack horses can help horse owners not only relieve their horse’s discomfort, but also provide a safe environment that can reduce the chances for diseases to spread. Flies are a nuisance to horses in three ways:
- By sponging or sopping up liquid on the horse’s face or body (the basic house fly and face fly)
- By piercing the skin to feed on the horse’s blood (stable flies, horn flies, horse flies, deer flies and mosquitoes)
- By laying eggs on the horse's throat, legs or nose (bot fly)
While house flies aren’t serious pests, they do carry diseases, can transmit stomach worms and cause annoyance—particularly by feeding on eye secretions. House flies breed during summer months and feed on filth, so proper stable management can reduce their numbers.
Adult female horse and deer flies are vicious biters, but they only feed during daylight hours. Controlling these flies can be difficult. Female flies lay their eggs in moist, swampy environments, so one way horse owners can control their numbers is by draining wetlands or using approved insecticides for larval control, according to the University of Tennessee Agricultural Extension Service. Because these flies ordinarily do not enter structures, providing the pasture horses access to a stable or barn during heavy attacks lessons the severity.
Stable flies, on the other hand, do live in barns and breed in organic, fermenting matter like manure or decaying straw. These flies usually feed on a horse’s legs; upon receiving the flies’ painful bites, a horse will stamp and kick to get the pests to go away. Stable flies cause substantial blood loss, transmit swamp fever and are vectors of “summer sores,” well known by horse owners as weeping wounds that are difficult to heal. Under heavy fly populations, insecticides may be applied to the horse’s legs every other day.
While there are great advancements in chemical control, sanitation is the best method of fly control, according to the University of Florida Institute of Food and Agricultural Sciences. They offer the following tips for stable managers to reduce fly populations:
- Thoroughly clean places where garbage, animal droppings or vegetation residues accumulate.
- Dry, spread or dispose of dog, cat or other animal excrement.
- Do not let garbage accumulate in the open, and make sure garbage cans have sound bottoms and tight-fitting lids.
- Keep tight-fitting screens on windows and doors. (In areas of high humidity, use copper, aluminum or plastic screens.)
- Keep waterers in good repair, and place them in well-drained areas away from where horses are fed.
Chemical control methods
Insecticides should never be the only method of fly control; however, most horse owners use them to round out their fly-control program. Without good debris management, insecticides will have little effect because the flies have a high reproductive potential.
Insecticides such as fogs and sprays can be used to deter adult flies living in stables, but because many chemicals break down so quickly, horse owners may find that relief is only temporary. According to the University of Minnesota Equine Research Center, residual premise sprays may be effective up to three weeks, depending on how dusty the stable is.
Fly repellents can provide temporary relief from attacking stable flies, which, under certain circumstances like horse shows, may be enough to keep horses comfortable for short time periods. Some of these products are safe to apply to a horse’s legs; they need to be reapplied after a horse walks through wet vegetation.
Insecticides come in a variety of applicators, including:
- Sprays and Wipes. Ingredients may be misted on with a pump-spray bottle, or applied with a sponge or cloth.
- Roll-ons and Towels. These products are best used to supplement fly control if flies are beginning to bite at specific areas.
- Spot-Ons. These are also concentrated products applied to specific sites. Watch for reactions including skin sensitivity, itchiness, redness, rash and hair discoloration or loss.
- Dusts. Insecticide is in the form of a talc or clay that is used in a specific area.
Researchers at The University of Kentucky offer special considerations when applying the above insecticides. Start by checking the label for instructions on re-treatment intervals and age requirements for foals. Before applying the product, brush your horse to remove dirt and dust. Brush the treatment lightly against the lay of the hair. When applying to the face, use a wipe to keep insecticides away from eyes and mucous membranes. Finally, if sensitivity occurs, bathe the horse with a non-insecticidal shampoo and thoroughly rinse.
Remember, whenever using an insecticide or other chemical control, be sure to read and follow all of the instructions on the product's label.
To achieve optimal results in equine pest management, it’s best to plan ahead. Are there certain pest-control strategies that you’ve used and would like share with other horse owners? Tell us your story in the comments section below!
“Horse Pest Management.” By Gene Burgess. The University of Tennessee Agricultural Extension Service. Accessed on July 31, 2010, at http://www.utextension.utk.edu/publications/pbfiles/pb1478.pdf.
“Insecticides for Fly Control on Horses.” By Lee Townsend. The University of Kentucky College of Agriculture. Accessed on July 31, 2010, at http://www.ca.uky.edu/entomology/entfacts/ef513.asp.
“External Parasites Around Animal Facilities.” By P. E. Kaufman, P. G. Koehler and J. F. Butler. University of Florida Institute of Food and Agricultural Sciences. Accessed July 31, 2010, at http://edis.ifas.ufl.edu/ig054.
“Fly Control Around Horses.” By Roger Moon, PhD, and Besy Gilkerson Wieland. The University of Minnesota Equine Research Center. Accessed July 31, 2010 at http://www.extension.umn.edu/distribution/livestocksystems/DI8537.pdf.