Warm weather plus horses unfortunately equals flies — nasty, biting flies that irritate horses and aggravate their owners. And they’re more than a nuisance; flies can spread parasites and the viruses and bacteria that cause several equine diseases.

Repellents and insecticides provide quick and effective relief, but if you want to control flies over the long term you’ll need a comprehensive strategy. Here are 12 suggestions to keep your horses more comfortable, and make your facility less hospitable — and even downright hostile — to winged pests.

1. Keep up with your waste removal program. It takes house and stable flies 10 to 21 days to go from egg to adulthood, so breaking their breeding cycle means getting fresh manure out of their reach weekly. Removing manure from the property would be ideal, but composting also works. In addition to manure, a compost pile can dispose of wood scraps, fallen leaves, grass clippings and other organic waste.

2. Spread manure selectively. Avoid spreading fresh manure over pastures that will be in use during fly season; when manure is spread, apply it in as thin a layer as possible so it dries out quickly. When spreading over crop fields, disk fresh manure under the surface of the ground to kill any eggs and larvae.

3. Repair leaking plumbing. Dripping water creates a moist environment ideal for fly eggs. Periodically check faucets, pipes and waterers for leaks, and when you repair them, fill in any puddles they’ve caused.

4. Keep stalls dry. Stable flies are attracted to the smell of urine, and they lay their eggs in urine-soaked bedding as well as manure. Remove wet bedding from stalls at least once, preferably twice, a day. Sprinkling a little hydrated lime over wet spots on the stall floor can help deodorize and dry them out — reducing their appeal to egg-layers.

5. Eliminate puddles and standing water. Stagnant water is an ideal breeding ground for several species of biting flies. Fill in potholes in your driveway, level areas where puddles routinely appear, and remove any debris, such as old tires, that collect rainwater. Make sure drainage and runoff systems around the barn are free of clogs.

6. Keep drinking water fresh. Rinse and refill water buckets daily; dump old water in an area where it won’t create puddles, preferably outside the barn or into a sink or drain. If a stall is vacant for more than a day, empty the water bucket and place it upside down to dry. Skim algae and floating debris from troughs daily and top them off with fresh water. One easy way of keeping troughs of 100 gallons or more clean is to add fish that eat algae, insects or larvae. Ask at your local aquarium store for recommendations about types of species and the number of fish that might work for you.

7. Set fly traps. Traps are an effective way of reducing the adult insect populations, but in general they work best in smaller, enclosed areas — and in conjunction with other methods of fly control.

• Baited traps. Baited traps can attract large numbers of house and stable flies, which are drawn into an inescapable chamber by the scent of an attractant, such as a sugary food.
• Tapes and glue traps. These strips, covered with an aromatic, sticky glue, catch curious house- and stableflies. They also catch dust and other airborne contaminants and need to be replaced every few weeks or as soon as they lose their stickiness.
• Physical traps. Baitless traps rely on the fact that horseflies are attracted to dark objects. A large round black ball attracts flies to land on it; when they do, they crawl upward to the top of the sphere; when they discover there is nothing here to eat, they fly up — and into netting that forms a cone above the ball; attracted by the clear space at the top of the cone, they continue to fly or climb upward, until they are trapped in the collection chamber.

8. Bug zappers. These familiar blue-light devices delivering a satisfying sizzle when flying insects hit the electric grid; one drawback is that they also attract beneficial bugs. As with any electrical appliance used in the barn, make sure the zapper is plugged in, grounded and secured where it can’t be knocked over. It’s also important to keep the trap clean to avoid a buildup of flammable dried bodies.

9. Outfit your horse with protective garments. A variety of products can prevent flies from reaching your horse’s sensitive skin. For turnout, try to discern which species of flies are bothering your horse. Ear nets protect against blackflies, while mesh leg wraps keep stable flies at bay. Masks protect against face flies, which like to congregate around the eyes. Light-colored fly sheets offer double protection: They are a barrier when flies land, and their brightness deters horseflies, which are attracted to dark colors.

10. Retreat from the midday sun. Many biting flies are most active in bright daylight, so keeping your horse stabled during when the sun’s at its highest can protect him from these pests. If you prefer to leave your horses in the pasture, make sure they have access to a deep, shady run-in shed. For added protection, hang long strips of burlap, carpet remnants, sheets or other fabrics in the doorway, to within two feet of ground level.

11. Apply repellents. Many effective commercial repellents are on the market as are numerous essential oils (including citronella, cedar oil, neem seed oil, eucalyptus oil, tea tree oil and lavender oil) which are common ingredients in repellents, both commercial and homemade. The first time you use any substance, be sure to check your horse for sensitivity; apply a small amount to a small area of your horse’s skin that doesn’t come in contact with tack and wait a few hours to see if a reaction occurs.

12. Harness the power of garlic. Ever notice how a distinct smell will stay on your breath and skin for hours or days after a garlicky meal? The strong oils in garlic are excreted through the skin and lungs, providing a potent scent that can repel insects. Fresh garlic can be tricky to feed to horses, but powdered garlic can easily be added to the feed. Start with a very small amount, until the horses get used to the new flavor and slowly increase the dose to a tablespoon or two each day.

This excerpt is from the article “25 Ways to Bolster Your Fly Control Program” which originally appeared in the May 2001 issue of EQUUS magazine.