Bye, Bye Flies!

Know Your Enemy

Sure, flies are annoying, but more importantly, they can be dangerous. Wes Watson, PhD, an assistant professor of entomology and an extension specialist at North Carolina State University, researches control strategies for pest management in livestock systems, including equine operations. He breaks horse-attacking flies into three groups and explains the inherent hazards of each:

• Nuisance flies, including house flies and face flies: Mechanical vectors of several pathogens and parasites; face flies can also damage the conjunctiva of the eye.
• Biting flies, including stable flies and horse flies: Take bloodmeals from the horse several times a day; bites are painful and often on the horse’s lower legs, which can make the horse stomp and become difficult to handle. Horse flies are known vectors of Equine Infectious Anemia.
• Myiasis-producing flies, including bot flies: Myiasis refers to the invasion of the organs and tissues of the horse by the fly larva. For example, bot fly eggs and larvae are ingested by the horse, then complete development while attached to tissues in the horse’s digestive tract. (The mature larva is excreted in the droppings to pupate on the ground and emerge as an adult.)

The house fly and stable fly tend to create the most problems around the barn, says Watson. That’s largely because they thrive in an environment rich in organic matter (manure, bedding, spoiled feed) and moisture (urine). The females of each species can lay about 200 eggs during their 10- to 14-day lifespan, and development (from egg to larvae to pupae to adult) takes as little as 10 to 14 days (with house flies developing faster than stable flies). You can see why fly populations explode so rapidly and why your best and first line of attack is to eliminate fly breeding grounds. In other words, clean up!

Attack the Home Front

You know that proper sanitation includes removing manure, soiled bedding and spilled feed from the barn. “But,” says Watson, “it’s also important to consider what happens to that material after it leaves the barn.”  

If you stockpile waste near the barn, he explains, you provide an ideal breeding site for flies. Instead, immediately spread the manure and bedding (i.e., on open areas away from the barn). This helps manure dry faster, thereby reducing its appeal as a fly breeding site. Composting is another option. Heat in the compost pile kills flies before they develop and the composting process leaves you with a material similar to organic soils, he says.