The Best Fly Protection for Horses
How to Get Rid of Flies Around Horses
Reading Time: 6 minutes
Biting flies can be a tremendous irritation to horses so finding the best fly protection for horses is essential. There are several methods of fly control on your farm and ways to protect horses from flies that come from other areas.
MINIMIZING FLY NUMBERS – Methods that can help reduce fly population on a farm include the use of premise sprays, fly traps, parasitic wasps, and feed-through larvicides. Some flies, especially horse flies, deer flies, and stable flies, can fly long distances and come to your farm from neighboring regions.
Around the barnyard, some horse owners believe that the best fly protection for horses is utilizing parasitic wasps — the harmless tiny wasps (sometimes called fly predators) that lay eggs in fresh manure. The wasp larvae feed on fly larvae and can help control flies that breed in manure. These wasps should be released early in the fly season. They only work on flies that lay eggs in manure, such as houseflies, horn flies, and stable flies.
Horse owners should try to control flies at the beginning of the warm season — whenever it occurs in their area before the insect populations become large. Try to get ahead of the curve by reducing early populations so there are not so many to reproduce. Cleaning up organic debris (old bedding and manure for gardens, decaying plant material that can become breeding sites) is very effective. Old hay or bedding should be removed or scattered so it can dry out. These flies must have moist decaying material in which to lay eggs. Don’t pile up organic material; a pile holds moisture and makes an ideal habitat for fly larvae. Some people pile up lawn clippings, which may supply enough stable flies to torment all the horses in the neighborhood.
Some people use a feed-through product added to the grain, and it goes on through the horse. Some of these contain a larvicide that kills fly larva that hatch in manure. Other products contain an insect growth regulator that hinders the growth of immature fly larvae, and they die.
Many horse owners think this method is safer than overhead fly sprays in barns because you don’t have to worry about contamination of feed, or irritation of the horses’ eyes. The feed-through products only work in the small area around a stable or pasture, however, and have no effect on flies that come in from neighboring areas. Another drawback to this method is that stable flies also breed in other materials, not just manure. People often become lax in the clean-up of old bedding and other organic material, thinking they have the problem under control.
FLY SPRAYS AND WIPE-ONS – There are dozens of sprays, wipe-ons, and spot-ons for use on horses, but almost all of them contain pyrethroids (such as permethrins) or pyrethrins as their active ingredients. These are about the only options, for effective products that are safe to use on horses. These are fast-acting, so you could apply them to the horse just before you plan to ride or work with the animal. Most products should be applied to the legs or belly since that’s where stable flies will be biting.
Spot-on products only need to be applied in a few locations on the horse, such as at the poll, tail head, at the point of each hock, and behind each knee. This seems to give protection for about two weeks. Spot-on products tend to last longer than most of the sprays and wipe-ons and also seem to work better for horses that are allergic to some of the sprays.
If biting midges (also called punkies or no-see-ums) are a problem, making horses itchy from an allergic sensitivity reaction to bites, these tiny flies can often be thwarted with diligent application of insecticide. Midges can make the animals miserable, and often bite along the midline of the belly — creating a crusty, itchy area. They are easiest to kill if you get enough insecticide on the animal and it stays on. Since they tend to feed on the belly, it is essential to apply it all along the belly and reapply it if the horse walks through tall grass, stands in a pond, or sweats.
Stable flies are hard to kill. They don’t spend much time on the animal so they don’t pick up enough insecticide to kill them. They zoom in, feed quickly, and fly away. Many of them survive to come back again a few days later.
The horse’s lower legs don’t retain insecticides very long. Even though a spray or wipe-on tends to bond to the hair after it dries, and is not easily rubbed off, it can still be washed off. Every time it rains, or the horse walks through wet grass or water, stands in a pond to protect himself from flies, or sweat runs down the legs, it washes off insecticide.
If the horse has been out in the rain or sweating a lot, you may need to reapply a product sooner than the label recommends. It’s difficult to keep enough on the legs to do much good, and the products that are effective need to be reapplied frequently.
Always follow directions when using any fly repellent or insecticide, to make sure you’ll get the optimum benefit from the product, without putting your horse’s health (or your own) at risk. Apply them in a well-ventilated area, and don’t handle or use these if you are pregnant.
Some horse owners try different methods, such as tying cattle ear tags (formulated for horn fly control) on the horse’s halter or braiding a fly tag into the mane, but this is a systemic type of control, which may not be good for your horse. Some of the cattle fly tags contain organophosphates, a more toxic type of chemical.
FLY TRAPS – Some flies are difficult to control with premise insecticides or manure management because they come in from other areas. Horse flies and deer flies usually emerge with the first hot days of summer, after their larvae develop in mud or water in marshy areas. Since they attack quickly and leave, most topical insecticides are not very effective against them. There are some fly traps that help, however. The University of Missouri has a website that shows how to construct a trap for horseflies.
There’s also a commercially available trap that works well for horse flies, deer flies, and other types of biting flies. The Epps Biting Fly Trap 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 tend to fly over, under, and around the legs of an animal before biting, striking the light-colored panels, and falling into soapy water in trays under the trap and drowning. The soap breaks the surface tension of the water and the flies can’t float — they immediately sink and drown. This trap is one of the best fly protection for horses techniques.
SIDEBAR: SENSITIVITY ISSUES – Some horses develop sensitivity to certain products. It’s important to not overdose. Read labels, apply the product correctly, in the proper locations and amounts, and always watch for any signs of skin reaction. Try it first on a small area of the body before you apply it all over the horse, to see if there is any type of skin reaction. It may take more than one application, however, before you know if the horse will react.
Some horses develop sensitivity over time. Everything seems fine, and then the horse has an allergic reaction after you’ve been using the product for a while. The horse may suddenly develop welts or hives.
Most insecticides contain petroleum products or alcohol, which are irritating to the eyes, mucous membranes, and genitalia. Never spray the horse’s face. If you need to apply it to the head, spray it onto a cloth and wipe it carefully on the face, avoiding mucous membranes. If you get too close to the mouth or the membranes of the nose, the animal may start salivating and sneezing.
SIDEBAR: PHYSICAL PROTECTION – In situations where flies can’t be fully controlled, fly masks can keep flies away from the horse’s face. There are also fly sheets that can help keep biting flies off the horse’s body and fly boots that cover the legs.
Originally published in the March/April 2022 issue of Countryside and Small Stock Journal and regularly vetted for accuracy.