6 Tips to Keep Pesky Flies Away From Horses

April 11, 2022

No good horse owner likes seeing their horse harassed by flies. The swishing, swatting and stomping can drive both a horse and rider to distraction. But flies on horses are more than annoying. They bite and irritate your horse’s skin, cause sores, deposit larvae and bacteria, and are carriers of disease. They can also make your horse nervous and interrupt performance. 

That's why fly control around barns and stables and inhibiting flies from landing on your horse is essential. Ready to take action to rid your horse of pests? You're in the right place! Let's cover the basics of  when fly season starts, what and why flies are harmful to horses, and helpful ways you can protect your equine in the battle of the bugs.


Quick Content Guide

When Does Fly Season Start?

Flies don’t care that your calendar says spring starts three weeks into March. They will start to surface, feed, and breed when it feels warm and comfortable enough for them to do so. The map below shows generic zones for when fly season begins and ends across the continental United States. Find your area to pin down the time period you need to be armed and ready for flies to attack. 

As a proactive measure, acquire your preferred fly-fighting supplies sometime during the winter. Purchasing early will help you be prepared if you experience an earlier-than-expected spring and outbreak. Once fly season is in full swing, plan for a battle that lasts well into the end of fall.  

when is fly season

What Kinds of Flies Are Attracted to Horses?

It's helpful to know the types of flies that land on horses, how they attack, and where they reproduce. Having this knowledge in your pocket can help you decide on prevention and treatment methods to mitigate these pests.

There are two main categories of flies: biting flies that feed on animal blood, and nonbiting flies that feed on bodily secretions. There are also other flies that lay eggs on horses. All are bad. And since the term “fly” is generic for any small, flying insect, that also includes gnats and mosquitoes.

Let’s take a closer look at the flies PennState Extension notes are most active in biting, bugging, and transmitting diseases in horses. Below you'll find a brief description of what each species looks like, where it lands, what it does, and how it spreads.

Stable Fly

  • Small body, grayish-black color.
  • Go for a horse's legs and flanks—ergo all that stomping. Has a painful bite that pierces the skin.
  • Lays eggs in decaying vegetation, manure and urine, contaminated hay or wet feed.

Horn Fly

  • Very small body—just half the size of a house fly but similar in look.
  • Typically found biting your horse's back or sides. 
  • Larvae develops in cow manure. If your horse isn't pastured with or near cows, horn flies probably aren't pestering your horse.

Horse Fly and Deer Fly

  • Horse flies have very large grayish-black bodies and green or purple eyes. Deer flies are smaller, with yellowish-orange and black bodies.
  • Both pack a powerful and painful bite. Horse flies may also carry equine infectious anemia (EIA).
  • Lay eggs in damp soil near streams, irrigation ditches, or lakes.

Black Fly

  • Tiny, humpbacked body. These tormenters gather in large swarms around horses.
  • Feed inside the ear, but also land on the head, neck, chest and abdomen. Bite can cause bleeding and itching.
  • Larvae develop in fast-moving rivers and streams.


Gnat (biting midges or small flies)

  • Very small, thin body. Yellowish, tan, or dark-brown in color.
  • Painful bite that may cause "sweet-itch" at the base of the mane and tail or over the withers, chest and face. 
  • Larvae develop around water, decaying vegetation, and manure.


  • Slender body and long legs—you know the look. Grayish color.
  • Feed on horses in large swarms and can produce surprisingly substantial blood loss.
  • Reproduce around marshes, irrigated pastures—anywhere standing water exists.

Face Fly and House Fly

  • Small body. Grayish-colored, with black stripes on the thorax. 
  • House and face flies are persistent pests that feed on the tear ducts of the eyes, around the nose, or on wounds and cuts.
  • Breed in fresh animal manure.

Bot Fly

  • Hairy, bumblebee appearance. Yellow face, metallic-colored body, and orange legs.
  • Lay eggs in areas the horse can reach with its mouth—like the forelegs, shoulders and lips. The eggs hatch when the horse licks and rubs them. Once in the mouth, bots burrow into the gums and tongue, and eventually enter the stomach. They detach in the spring and pass through the feces.
  • Larvae pupate in manure, mature flies emerge,  mate, and lay eggs to start the cycle over.

What Diseases Can Horses Get from Flies?

On the surface, flies and gnats can cause itching, hives, hair loss, skin thickening, abrasions, and ulcerations. Each of these conditions leave your horse susceptible to bacteria and infection. While that's distressing enough, the problems perpetuated by flies go more than skin deep. Here are some common diseases spread by flies (including gnats and mosquitoes) on horses:

  • Summer sores: Nonhealing wounds caused by larvae from house, face, and stable flies. 
  • Pigeon fever: Bacterial infection deposited by flies on broken skin. Causes large abscesses on a horse's chest or underbelly.
  • West Nile Virus: Mosquito-borne virus that may cause neurologic disease. 
  • Equine Infectious Anemia: Serious blood-borne virus carried by horse flies. Symptoms vary from a slight fever, to weakness, weight loss, or disorientation.
  • Equine Encephalitis: Mosquito-borne disease that causes inflammation of the brain and spinal cord.
  • Sweet Itch: An allergic condition triggered by gnat bites. Causes mane/tail rubbing and damage to the skin along the upper neck, back and tail base.

Watch the short video below with Dr. Jessica Huntington  to get her take on biting insects, vector diseases, and natural fly control treatment.

HubSpot Video

6 Tips to Create a No-Fly Zone Around Your Horse  

Even conscientious horse owners can sometimes feel like they're losing the battle of the bugs around stalls and barns. A fly infestation is frustrating for you and especially your horse—since it really only has a tail to use to drive away flies.

The good news is you have quite a few options to  fight flies on all fronts. Here are a variety of fly deterrents that either block, repel, or reduce  insects so you can keep yourself, your horses and other animals comfortable during fly season.

1. Use a Quality Feed-Through

Feed-through fly control can be an effective means to reduce the overall fly population on your property. A horse feed-through is a larvicide—it kills larvae from flies or mosquitoes before they mature into adults. As the name suggests, a feed-through is an additive fed to horses in the form of pellets. The active ingredient is mixed into the horse's manure through ingestion and digestion which stops the development of larvae and future flies in manure.

While larvicides are not supposed to absorb into a horse's gastrointestinal tract, some horse owners may feel concern about feeding this type of product. If you pick a feed-through as one of your fly control methods, make sure you're informed about the product and feel comfortable giving it to your horse. If you're looking for a completely feedable, all natural fly repellent for horses that repels flies, click here to skip to the bottom of the article.

2.  Add Outer Fly Protection for Horses

Layering on protection from the outside is a great way to block pests and help your horse stay fly free. You can get gear to protect them from head to hoof. There are mesh fly masks and boots, hoods, bonnets, veils, and fly sheets that fit your horse’s body—and all in a variety of colors and prints to suit your horse’s fashion style.  Aside from picking your favorite print, we recommend choosing a material that’s comfortable for your horse, cool, and durable enough to last the season. Check out this blog for more recommendations on choosing a fly sheet and the best brands.

3. Repel with  a  Horse Fly Spray

A good fly spray is essential to have on hand in the barn, when traveling, and during those sweltering summer days when flies just get out of control. These products repel insects and can be sprayed or wiped on, especially for application around the eyes. Horse fly sprays can last anywhere from several hours to several days, depending on the ingredients and if it’s oil- or water-based. To help you feel more informed about your choices, this University of Kentucky article lists popular brands of spray and wipe-on repellents, plus the active ingredient and concentration in each brand.

At Redmond, we believe natural is better for our equine friends. So always check ingredients, and perhaps look for a spray containing essential oils or other natural repellants. If you do choose a commercial spray, Pyranha fly spray for horses is a brand we like. Also, before covering your horse, make sure to test a small patch area to check for sensitivity or irritation to any product.

4. Set Out Fly Traps  and Fans

From sticky tape to bug zappers, traps are a satisfying way to reduce the overall population of flies around your barn or property. Location, location, location is the key here.    

If you’re using sticky traps, place them up high in barns or stalls where light and warmth reach and where your horse can’t.  Using an odor trap? Place it at least 50 feet from your barn or paddock. This will ensure you lure flies away from your horse instead of drawing them in. Bug zappers or other visual attractants should be placed just outside of paddocks, fences or stalls—close enough to be effective but far enough away that your horse can’t tamper with it.  And for best results, set your traps out by mid-spring, before flies begin laying eggs and become a bigger problem. 

For stalled horses in enclosed barns, adding a high-powered fan that points outward at entrances will also limit the number of pests getting in the door. 

5. Use Biological Fly Control

You've heard of fighting fire with fire. Some companies offer a way to wage biological warfare on flies and reduce the overall population using parasites. Here's how it works: gnat-sized wasps (biteless and stingless) are released around your farm, stables, and pastures. The females seek out organic material like manure to deposit their eggs inside fly pupae. The eggs then hatch, feed on developing flies, and stop them from hatching. Since pest flies reproduce at a faster rate, fly predators need to be released every three to four weeks throughout fly season to remain viable. However, they're another safe and organic weapon in your fly-fighting arsenal.

6.  Reduce Standing Water  and Keep Your Horse’s Area Clean

While it means some extra work for you, keeping a tidy stall, paddock or barn helps reduce flies and can go a long way in keeping your horse comfortable. Getting rid of organic debris and managing water sources is one of the most effective ways to control flies.

Fresh manure is a breeding ground for flies. Removing it regularly—along with soiled or wet bedding and feed—will limit flies congregating and laying eggs in your horse’s space. Once you've removed the manure or organic material, disc or spread it out instead of heaping it in a pile. This breaks it up, dries it out, and makes it far less habitable for pests. 

Also, make sure your horse’s water is clean and fresh. Any source of stagnant or smelly water will attract gnats, mosquitoes and certain types of flies—none of which you want moving in with your horse.  Tip over or get rid of containers that collect water. If you can't remove standing water from an area, adding minnows to small ponds or your horse's trough is a natural way to inhibit mosquito breeding. Larvicides with  the bacterium Bacillus thuringiensis israelensis (Bti) or the insect growth regulator methoprene can also be added to ponds to kill larvae, and is considered safe for livestock.

What to Feed Horses to Repel Flies 

Besides external fly-fighting measures around your horse and barn, many horse owners also want to know what to feed  horses to repel flies. Did you know garlic is one of the best and most natural horse fly repellents? Proponents have argued for years that it reduces flies on livestocknow there are numbers to prove it. In 2017, researchers in Saskatchewan determined cows fed with a trace mineral salt fortified with garlic had 52% fewer flies than control groups that received trace mineral salt alone.  


Best Natural Fly Repellent for Horses 

Looking for fly relief for your horses? Redmond Rock Crushed with Garlic is Redmond's loose trace mineral salt fortified with the power of garlic. Crushed Garlic is a great choice as a health booster and natural fly supplement for horses. It contains bioidentical garlic oil—the most bioactive, stable, and potent form of garlic. In addition, it delivers 60+ trace minerals your horse needs for optimum nutrition and hydration

Crushed with Garlic is what we call a "sweat-through" repellent that offers your horse protection from the inside out. As a horse consumes the mineral salt, garlic is absorbed into the blood stream and sweat out through the pores to repel flies, ticks, and other insects. Read this testimonial from Crushed with Garlic customer Staci M. Fife:

"I've been feeding this for 2 weeks. All 3 eat it with no issues, and best of all, I don't see any new welts, bumps or itchy spots on my sensitive skinned filly. Her eyes are less watery, and she seems so much more comfortable, with way less fly spray, and not bundled in a fly sheet in 100 degree weather." 

Give your horse a delicious mineral supplement and fly repellent that works! With Redmond Rock Crushed with Garlic, your horse will receive valuable health benefits, experience less flies, and feel more comfortable. Click below to try it today!


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