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8 tips for practicing non-toxic fly control for horses

June 16, 2021

Horse owners are not destined to fail during the summer. Protect your horse and your farm with these non-toxic tips for insect and fly control.

Horse owners often wrongly believe that they are destined to put up with a high number of flies and insects. As mid-summer approaches and heat and dry weather become the norm, many parts of North America are likely to experience an onslaught of fly populations, while other parts of the country are likely to have intense mosquito issues. Additional troublesome insects, such as biting midges — often called “no-see-ums” or buffalo gnats — can make summer almost unbearable for horses.

All of this makes many of us horse owners want to resort to utilizing heavy-hitting chemicals to keep our animals comfortable. While there may be a time and a place for this type of chemical warfare, looking at some big-picture management options is the safest way to begin your warfare strategy and reduce the need for insecticides. You should waste no time in planning your attack on the coming season’s flies and insects.

In this blog, I will review some of the least-toxic, most environmentally friendly methods for reducing and managing the fly and insect population at your horse facility, including diminishing the insect habitat, using mechanical barriers, putting beneficial insects and native birds to work for you, and setting non-insecticidal traps. We will also cover the topic of insecticides so that, if using these products becomes necessary, you can make an informed decision.

Using these controls as your first line of defense will help you reduce both the amount of chemicals used around your property and your impact on the environment. Less flies and fewer chemicals will be healthier for you and your horses, all while promoting sustainability in the equine industry.

1. Practice manure management.

Insecticides and fly sprays are commonly used in livestock fly control protocols, but you can greatly reduce your dependence on them if your manure and mud are managed properly, as flies, mosquitoes and other pests depend on manure and mud as a breeding ground.

Start with picking up the manure in stalls and confinement areas on a regular basis and developing a composting or manure storage area. Composting manure is the best option, as flies are generally associated with fresh manure rather than compost. A simple cover or tarp helps prevent rain runoff, which can contaminate surface water, creating the muddier habitat in which insect pests prefer to breed.

Gutters and downspouts on farm buildings divert clean rainwater away from animal confinement areas, reducing the chance of mud and the amount of water and mud in which insects could live. 

Stagnant water — that is, water that has not been moved or added to for five to seven days — can become a breeding site for mosquitoes in levels as small as half of a teacup. Flies and other pests also need water to survive, so it’s important to eliminate unnecessary sources of water, such as leaky faucets. Get rid of anything lying around that can hold stagnant water, such as old tires, toys, flowerpots, birdbaths, dog water bowls, buckets, barrels or trash.

Some insects — including face flies, biting midges, and deer or horse flies — do not like to enter darkened barns or stables. Providing your horse with a shelter or putting them inside a barn before and during dusk (when these insects are most active) may help horses escape being attacked by these miserable creatures.

Biting midges and mosquitoes tend to be poor flyers, so offering good ventilation or safely placing a fan outside a stall can create air movement, which may help individual horses that are particularly tormented by bugs.

2. Prioritize pasture management for horses.

Whenever possible, graze horses on higher, drier pastures at the beginning of the summer to avoid creating muddy areas. Save the lower, wet pastures — which harbor mosquitoes, deer flies, horse flies and biting midges — until later in the summer when those areas dry out.

Harrow (or drag) your pastures regularly to break up manure piles. Harrowing spreads manure, allowing plants to utilize the nutrients and organic materials contained therein. Spreading also dries out manure, making it a less attractive habitat for flies. 


Using footing materials — such as finely crushed gravel (sized 5/8 of an inch or less) or coarse sand — in confinement areas helps to further reduce mud. Three to six inches of footing material will help build up the area, keeping horses up out of the dirt and allowing rainwater to drain through.

3. Use physical barriers.

Most horse owners know about one wonderfully safe and effective method of fly management for horses: the fly mask. Fly masks act as a physical barrier between the horse and flies, with the added benefit of being a sunscreen for horses that are sensitive to sunburn. Most horses learn to appreciate fly masks quickly and will willingly lower their heads to have a mask put on them. Some masks only protect the eyes, while others also protect ears and jowls.

Fly sheets are an additional option. These cool, open-weave, lightweight horse blankets can be quite useful at keeping pestering flies off a horse’s body. Fly boots are also available to help protect the horse's legs and hooves by helping to greatly decrease stomping.

4. Recognize good bugs.

When it comes to pest management, we often err by approaching all insects as pests. However, according to the Xerces Society — a forty-year-old nonprofit organization that works to conserve habitats for beneficial insects worldwide — only about 2% of all insects are actually considered pests. The Xerces Society also reports that beneficial insects are worth quite a bit to agriculture economically: around $4–12 billion annually. Many insects prey on each other, and insects would rule the world if that were not the case.

One example of a beneficial insect that horse owners can put to work is the fly parasite, a gnat-sized, nocturnal wasp that lays its eggs in the developing pupae of flies, thereby reducing or nearly eliminating the fly population. Fly parasites do not harm humans or animals in any way and are rarely even noticeable, since they are tiny and are only active at night.

Commercially raised fly parasites can be purchased from several sources, which can be located by doing an internet search of the words “fly parasite”. To be most effective as a fly control program, fly parasites should be released early in the fly season and every four weeks thereafter.

5. Encourage insect-eating birds.

Encouraging insect-eating birds to move into your yard and barn area is an excellent method for reducing the flying insect population. Members of the swallow family can be a tremendous asset to a horse facility, as they dive and dart through the neighborhood collecting bugs. One adult barn swallow will consume several thousand insects per day — a number comparable with using a bug zapper via a method that is much safer than using insecticides.

Some common North American insect-eating birds include violet-green swallows, tree swallows, barn swallows, bluebirds, purple martins and cliff swallows. Nesting can be encouraged by hanging nest boxes specifically made for the types of birds in your area. Swallows, such as violet-greens, will utilize nesting material like hair that is shed by horses or dogs. For help determining the insect-eating birds specific to your part of the country and their nest box needs, consult your local Audubon Society, birding organization, extension office, wild bird store or library.

6. Accept bats.

Bats play an important part in every healthy environment by eating the nocturnal flying insects that plague both our horses and ourselves, such as mosquitoes. Bats are reported to eat up to 600 mosquitoes an hour — more than 5,000 a night! They also eat other agricultural pests, such as corn borers, cutworm moths, potato beetles and grasshoppers.

You may be able to encourage a bat family to move onto your property by hanging a bat box built specifically for the types of bats common in your region. Bat houses should be placed on the southern exposure of a barn, pole, tree or house. The best habitat is within a half-mile of a stream, lake or wetland. Place bat houses by early April and be patient, as it may take up to two years for a bat colony to find your house.

A word of caution: Because of the concern for rabies, which can be carried by bats (as well as any warm-blooded animal), consult your veterinarian for their recommendations on vaccinating your horses against rabies. And just as you would do with a stinging insect or an unfamiliar dog, always leave bats alone. Bats are not aggressive, but like any wild animal, if cornered, they may bite to defend themselves.

7. Use insect and fly traps.

Several types of simple, non-toxic insect traps can be extremely useful for reducing the flying insect population on your farm. The cheapest and easiest are sticky traps; flying insects happen across them and get stuck. Fly paper or sticky tape can be attached above doorways or from barn ceilings. Old-fashioned sticky strips — the coiled kind — are probably the cheapest and easiest to utilize. Try hanging many of them (i.e., 10 or more) from your barn ceiling. Once they are full of dead flies, remove the old pieces of tape and hang fresh ones. Choose these locations carefully to avoid snagging human hair or swishing horse tails.

Other kinds of traps include brightly colored sticky tubes, as bright colors attract flies; these tubes can also be hung up. These traps may or may not come with an attractant (i.e., an embedded scent), which flies seek out.

Several commercial brands of pesticide-free bags are available on the market. The stinky attractant used in these bags activates when dissolved in water. Lured by the scent (and perhaps also the color), flies enter the trap through the yellow cap top and drown in the water. These bags come ready to hang and use and are easy to dispose of when full by simply tossing into the trash. There are also reusable varieties.

Place attractant bags on the perimeter of your property to lure flies away from high-traffic areas. The downside to these traps is that they are smelly — which is another good reason to place them away from barn areas.

8. Understand your chemical control options.  

An insecticide is a chemical that kills insects, while a repellant is a substance that discourages flies and other insects from landing. When using insecticides, read and follow the directions carefully and avoid using more than necessary. Only use insecticides that are recommended for use on horses. Generally, insecticides are meant to be used outdoors, in well-ventilated, open places — not in an enclosed area, such as an indoor stall or barn. Indiscriminate use of insecticides may promote resistant strains of flies and could kill beneficial insects or harm birds and bats.

Equine insecticides generally fall into one of four categories (listed here in order from least to most toxic):

  • Pyrethrins (a botanical insecticide made from chrysanthemums)
  • Permethrins (synthetic pyrethrins)
  • Carbamates
  • Organophosphates

Unfortunately, “least toxic” and “most effective” don’t always go hand in hand. Even the best fly sprays containing pyrethroids do not last long.

Insecticides are usually used as premise sprays, which means that any insect they come into contact with will potentially be killed — including beneficial ones, not just pests.

Most equine fly sprays are repellents. Repellents are available as sprays, lotions, wipe-ons, gels, dusting powders, ointments, roll-ons, shampoos and towelettes. Repellents contain a substance irritating to flies, such as oil of citronella, and most contain some amount of insecticide.

Repellents also contain a product, known as a base, that helps hold the active ingredients to the horse’s body hair. The most common repellent bases are water, oil or alcohol. Oil-based repellents remain on the horse’s hair shaft longer, but oil attracts dirt. Water-based repellents do not last as long but attract less dirt, and alcohol-based repellents can be drying to the horse’s skin. To increase the lasting effect, some repellents are made with silicone, which coats the hair shaft and holds the repellent in place longer. Repellents can also contain sunscreen, coat conditioners (such as lanolin or aloe vera) and other products that may increase their staying power. How long a repellent lasts depends on the weather, the exercise level of the horse (i.e., how much they sweat), brushing and rolling.

Moderation is key. Sometimes chemicals must be used, especially on insect-sensitive horses, but it is best to avoid spraying the horses every day or while they are in their stalls or pens; that’s a lot of chemicals to put on the horse, and it may also be very costly.

Say goodbye to the bugs in the horse barn.

The key point to keep in mind when trying to manage insects is to first strive to diminish the insect habitats where insects live and breed, which include mud, manure and stagnant water. After you have these areas under control, go after insects with birds, bats, fly parasites and non-insecticidal traps.

Beyond that, if certain insects become problematic, you can choose whether you want to use a repellent or an insecticide-based spray on your horse. With these tools on hand, you’ll have more options available for the coming insect season, meaning you won’t have to put up with as many pests and can also reduce the use of chemicals on your horse property.

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