Dead On the Spot

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Fly season is upon us, so here are a few tips to get ahead of these pesky critters. This is the first of a two-part series on fly control—stay tuned for feed-through solutions on May 21. And check out the photo gallery.

Dr. Nancy Hinkle, entomologist (University of Georgia), says horse professionals should take steps to control flies/mosquitoes at the beginning of fly season—before the insect population becomes large. There are many species, with different life cycle and habits, so best results are obtained by a multi-pronged attack, using premise sprays and fly traps, as well as repellents and insecticides on the horses themselves.


There are dozens of sprays, wipe-ons and spot-ons for use on horses that can be found at any tack or feed store. These fall into three categories—long-lasting (effective for multiple days, such as UltraShield EX and Endure), daily application (effective for 24 hours, such as Bronco, Bronco Gold, Flysect and Wipe II) and “natural” (such as UltraShield Green, Deo-Lotion, Flysect Citronella, Equisect and EcoPellent Spray).

Most insecticide products contain pyrethroids (such as permethrins) or pyrethrins as active ingredients. “These are about the only options for effective products that are safe to use on horses,” says Hinkle. “Most products should be applied to the legs and belly, since that’s where stable flies will be biting.”

Dennis French, DVM, University of Illinois, says Ultraspot, made by Absorbine, works well. “This liquid spot-on is a 45% permethrin, applied in six different spots. Each tube contains six milliliters—enough to treat one horse. You put one milliliter at the poll, another at the tail head, and on a spot above each hock and behind each knee,” explains French. Spot-on products tend to last longer than most sprays and wipe-ons and seem to work better for horses allergic to, or afraid of, sprays. Low-volume, high-concentration pyrethroids work fairly well to deter horse flies and deer flies.

If biting midges (punkies or no-see-ums) make horses itchy from an allergic sensitivity reaction (“sweet itch”), these tiny flies can be thwarted with diligent application of insecticide. “Midges often bite along the midline of the belly and create a crusty, itchy area,” says Hinkle. “They are easiest to kill if you get enough insecticide on the animal and it stays on. Apply it all along the belly, and reapply it if the horse walks through tall grass, stands in a pond, or sweats,” she says.

Even though the spray or wipe-on bonds to the hair after it dries, and is not easily rubbed off, it can be washed off. “Every time the horse walks through wet grass or water, stands in a pond, or sweat runs down the legs, it washes off,” says Hinkle. And, if the horse has been out in the rain, you may need to reapply a product sooner than the label recommends.

Dr. Tia Nelson (veterinarian, Helena, Montana) uses a variety of products. “We make one ourselves, which can be used as a wipe-on or spray. We use one-quarter vinegar, three-quarters water and just enough citronella oil to make it really fragrant. If I make up a gallon I might add a half-tablespoon of citronella oil. With some horses it seems you need a little more citronella to be effective. I feel this type of repellent is kinder to the horse’s body than some of the pyrethrins,” she says. Another option is Skin-So-Soft, from Avon, or EcoPellent spray.

Always follow directions when using any repellent or insecticide, to get optimum benefit without putting a horse’s health (or your own) at risk. For example, “The label for Equi-Spot, by Farnam, says it’s for external use on horses only, use in a well ventilated area, and don’t handle or use it if you are pregnant,” explains Nelson.

Another option preferred by some horse professionals are fly sheets with built-in insect repellent. This protection is long-lasting—for 25 launderings or six months of continuous outdoor use. A new product, Fly Armor, consists of fly-repellent bands that can be placed on a horse’s halter or bridle.


Several insecticide products can be used in barns, including aerosol bombs and spray kits. The latter release an insecticide spray or mist on a timed schedule. The Pyranha Spray Master system is a 55-gallon fly control product than can treat up to an 80-stall barn.

For horsemen who don’t want harsh chemicals, the Barn Friendly EcoPellent (which incorporates natural oils and waxes) can be hung in the barn for a slow-release vapor. Each package repels flying insects within a 2,500-square-foot area (6- to 8-stall center-aisle barn).

Some types of flies are difficult to control with premise insecticides because they come from other areas. Horse flies and deer flies emerge on the first hot days of summer, after the larvae have developed in mud or water in marshy areas. “We usually can’t control the source of these flies; they may come from miles away. Since they attack a horse so quickly and leave, most topical insecticides are not very effective against them,” says Hinkle. “Some fly traps help. The University of Missouri has a website that shows how to construct a trap for horseflies (”

A commercially available trap that works well for horse flies, deer flies and several other biting flies is the Epps Biting Fly Trap, invented by a cattleman in Oklahoma (and now marketed by Horseline Products). It uses a dark-colored panel to simulate the silhouette of an animal, and light-colored panels above and below it. Horse flies and deer flies fly over, under and around the legs of an animal before biting, so they strike the light colored panels and fall into soapy water in trays under the trap, and drown. Soap breaks the surface tension of the water and the flies can’t float—they immediately sink.

“Some of my colleagues say it is very effective,” says Hinkle. “These types of traps may not completely control flies, but they do cut down on the number.”

There are also physical traps that contain fly pheromones as bait. There are fly tapes, ribbons and fly sticks that attract insects and they become stuck. Mosquito Dunks and Bits can be sprinkled in standing water to keep mosquitoes from breeding, and are safe to use in drinking water.

In the war against flies, it is important to coordinate strategies for various products to use them to best advantage and not in counterproductive ways. For example, insecticides around the barnyard kill beneficial predator wasps. Fly baits and attractants inside your barn draw flies into your barn so these should be placed in a different location than where your horses are. So, use an integrated approach, but with a logical plan.

And don’t forget that manure is a favorite breeding ground for flies, as standing water is for mosquitoes. Tackling a few barn management issues can greatly reduce the number of pests in your barn.

Here are a few websites to get you started on your fly control program:

Surface fly control (sprays, sheets, roll-ons, etc.)

Facility and area fly control