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How to Manage Flies Around Horses

Reprinted from

When the lighter evenings and warmer weather arrive, you can look forward to taking off your horse’s rugs and riding outside in the fresh air and sunshine. Unfortunately, the summer weather brings with it the menace of flies. Flies can make every aspect of horse care unpleasant.

Whether it be swarms of buzzing insects hanging around the muck heap, to biting species, such as horse flies that can send the most chilled-out horse crazy, or invisible midges that bring on the misery of sweet itch, flies are the most unwelcome of summer visitors.

In this article, we take a look at how you can banish the biting, buzzing critters from your barn, your horse, and yourself!

What’s so bad about flies?

Well, everyone knows that flies are annoying and irritating to both horses and their owners. But flies can also potentially make your horse sick by spreading diseases, including:

  • vesicular stomatitis

  • salmonella

  • pigeon fever

  • equine influenza

  • infectious anemia

Also, flies can trigger allergies, eye conditions, such as conjunctivitis, and dermatitis. A horse that constantly stamps to try to deter flies can develop ringbone, arthritis, and other concussive injuries, not to mention causing his shoes to come loose or be lost altogether.

Constant harassment by flies can interrupt a horse’s grazing time and prevent him from resting, leading to a stressed horse that drops weight or even injures himself as he tries to escape the flies’ relentless assaults.

Types of flies

There are many species of flying menace that affect horses and their owners, the following seven being the worst offenders:

1. Stable fly

  • Stable flies bite the horse so that they can feed on his blood.

  • To evade the biting bugs, horses stamp and constantly swish their tails.

2. Housefly

  • House flies have sponge-like mouths and suck up secretions from the horse’s eyes, nostrils, and anus.

  • You’ll also see these delightful creatures feeding on manure and garbage. Nice!

3. Face fly

  • Female face flies feed on the secretions around your horse’s nostrils and eyes and on the blood from wounds and skin punctures caused by biting flies.

  • Face flies have rough tongues that abrade the tissue around the horse’s eyes, stimulating a flow of tears, causing infection and even blindness.

4. Horn fly

  • Horn flies are small, about half the size of a housefly. Although more commonly seen around cattle, they do attack horses, biting the victim’s skin and sucking their blood.

  • Once a horn fly finds a suitable host, it will remain with that animal until the fly dies.

5. Bot flies

  • Bot flies lay clutches of sticky, yellow eggs on the horse’s coat, typically on the inside of the legs and around the face. The horse ingests the eggs by licking them off. The fly larvae hatch in the horse’s mouth, before migrating to the animal’s stomach and intestines. Untreated bot fly infestation can lead to a loss of condition in the horse and can even cause death.

  • All horses should be wormed against bots every year.

6. Gnats and midges

  • Gnats and midges are also known as “no-see-ems.” These are tiny flies that bite the horse’s skin, causing sweet itch.

  • Horses with sweet itch suffer from persistent, extremely itchy skin break-outs, typically on the top of the tail and along the mane and crest. The constant itching drives the horse crazy so that he scratches and rubs the areas raw in an attempt to relieve the discomfort.

  • Gnats are most active during dusk and dawn, so, if possible, stable your horse at these times. Also, spray the horse with an oil-based fly repellent spray. The oil forms a protective barrier over the horse’s skin, preventing the tiny gnats from biting.

7. Horseflies

  • Horseflies are most commonly seen near wooded areas, especially if there are cattle on adjacent pastures. These large, solitary insects are poor fliers, and they don’t like bright sunlight. That’s why you’ll always find these biting insects lurking in the shade provided by tree canopies.

  • Horseflies bite their victims so that they can feed on the animal’s blood. Note that horse flies will also bite people and short-coated pets.

  • Horsefly season is typically from June through July, so if your land is plagued by them, you might need to keep your horse stabled at this time. Although some repellents can be very effective, horse flies are capable of biting through thin mesh, so fly masks and sheets might not be much use against these vicious pests.

Preventing flies

Before we take a look at how to deal with nuisance flies head-on, let’s consider how you can prevent an infestation in the first place.

Moisture control

All insects are attracted to wet areas where they can drink and breed. So, take steps to keep your stables and yard dry and free-from pools of standing water in low-lying areas.

Repair leaky faucets, cover rain barrels and fix holes in the yard surface where water gathers.

Muck management

Manure is a magnet for houseflies.

Make sure that stalls, loose boxes, and pens are mucked-out daily. Ideally, have your main muck heap removed to an off-site location once a week. Alternatively, cover the muck heap with a heavy tarp for removal at a later date.

If possible, site the main muck heap well away from your barn or yard.

Once the muck is dry, it’s not as attractive to flies, as they feed on the wet secretions within the manure. So, breaking up and spreading manure across pastures can remove the need for daily poo-picking, especially across a very expansive acreage, while effectively removing the flies’ feeding grounds at the same time.

Alternatively, invest in an automatic poo-picker attachment that will fit a small tractor or quad. Invest some time each day in removing droppings from small areas of pasture to help to keep fly numbers down.

Install fans

Flies are generally very weak flyers, and you can use that to your advantage by placing large fans in your barn.

Aim the fans so that they are facing away from the horses to create turbulence that the insects cannot fly through.

Wide-open spaces

Flies can be a menace to grass-kept horses. Using the same principle as you did in your barn, turn your horses out in open, breezy fields where insects will struggle to fly against the wind.

Choose neighbors carefully

If possible, avoid using paddocks and fields that are adjacent to cattle and other livestock. Cattle are notorious for attracting myriad flies, some of which have a vicious bite.

Keep food covered up

Garbage and food remnants attract flies. Use airtight lids on yard trash cans and securely cover other foodstuffs, such as carrots and coarse mixes.

Keep it dark

Many fly species avoid dark spaces. Use that to your advantage by turning off your barn lights at night to avoid attracting insects.

Throw out decaying hay

Biting stable flies are attracted to heaps of moldy, soiled hay in which they can breed. Break the flies’ life cycle by disposing of old, decaying hay from stalls, paddocks, storage areas, and from dark corners of your barn.

Wage war against flies!

As well as taking action to manage flies, you should equip yourself with an arsenal of weapons to wage war against the flying fiends!

Topical treatments

Topical treatments can be used as repellents to keep flies away. Some treatments contain natural and/or synthetic insecticides that can “knock down” or deter flies. Products that don’t contain insecticides act as repellents.

Although topicals are easy to apply, coming in the form of roll-ons, sprays, or wipes, their effect is usually short-lived. Most of these products need to be applied daily or at least weekly to remain effective.

Topicals work best when used in conjunction with feed-through products or fly parasites that kill fly larvae before the insects reach the adult stage.

The cost of topicals varies, depending on the ingredients and the form of application. Bear in mind that usually, the lower the cost of the product, the shorter the duration of protection.

Physical barriers

Physical barriers to flies can be highly effective, especially for horses that are turned out at pasture during the day.

On the downside, you will need to spend quite a bit of time putting on and taking them off and some horses are very adept at removing them overnight! Also, these products can be quite expensive to buy and maintain.

Fly sheets

  • These are lightweight mesh rugs that cover the horse from withers to rump, and some provide protection for the horse’s neck, belly, and chest too.

  • Fly sheets, etc., are made from a lightweight mesh fabric that prevents the horse from overheating. Many barrier products offer the horse UV protection, too, making them ideal for horses with exposed pink skin and preventing the coat from bleaching.

Fly masks

  • These give the horse protection for critical facial areas, including the eyes, ears, and muzzle, depending on the style.

  • Fly masks are very effective at preventing conjunctivitis that can be caused by fly activity around the horse’s eyes.

  • Also, a physical barrier will prevent biting flies from attacking the sensitive areas of your horse’s face. That said, it is advisable to remove fly masks at night and during heavy rain, as they can obscure the horse’s vision.

Fly boots

  • These cover the sensitive skin on the horse’s lower legs, where bot flies often lay their eggs.

Fly bonnets

  • Fly bonnets are designed to cover the horse’s ears, poll, and forehead, preventing flies from bothering your horse while you’re riding. These cute, knitted bonnets can be color-coordinated to match your riding jacket too.

  • If you have a sensitive horse who throws and shakes his head when flies are hanging around, a fly bonnet might be the answer to your prayers, especially if you compete in dressage classes where unsteadiness to the contact is a big mark-loser.

Fly traps

A fly trap can be a great idea for your barn, feed room, and communal areas.

Traps come in many different forms, but they all use some form of bait to lure flies into a receptacle or onto a sticky surface, where the insects eventually die.

Although they are undoubtedly effective, fly traps only attract house flies and blowflies. If you have horse flies, stable flies, and gnats, you will need a different type of trap. Also, most traps have a shelf-life, so you’ll need to replace them to maintain their efficacy. That said, fly traps are extremely effective in controlling adult fly populations, and most are relatively inexpensive.

Barn spray systems

Barn spray systems are designed to kill insects, mosquitoes, and flies on contact with the insecticide that they contain.

Barn spray systems consist of a network of tubing that runs through the facility. Attached to the pipework are misting nozzles that periodically deliver a haze of fine droplets that contain a fast-acting, airborne pyrethrum insecticide.

Once set up, spray systems are highly effective and efficient, killing flies quickly before they have a chance to pass on any immunities to the insecticide. Pyrethrum is biodegradable and eco-friendly, biodegrading within 30 minutes of spraying.

The main drawback to barn spray systems is that they are very expensive to install, and the tank will need to be refilled every few months. These systems can be unsuitable for people and horses who are sensitive to the chemicals that the insecticide contains. Also, beneficial insects, such as spiders, will be killed by the spray.

Fly parasites

Fly parasites are tiny wasps that kill the fly pupa before they hatch, preventing new generations of flies from maturing. There are no chemicals to worry about, the wasps don’t kill beneficial insects, and they don’t bite people, pets, or horses.

Unfortunately, fly parasites don’t affect horseflies or deer flies.

So, once you’ve received the fly parasites, they take about five days to emerge from pupa. Once released, it can take up to a month before you see any noticeable results because the wasps don’t affect mature flies that have already hatched. For best results, release the parasites at the beginning of the season, before the flies become really active.

Once the wasps are in circulation, you’ll only need to release new ones every three to four weeks.

Natural predators

Many species of birds eat flies. So, encouraging wild birds to hang around your barn and muck heap can be a good way of reducing fly numbers. However, bird droppings also make a mess around your yard, and nesting material can look unsightly.

Bats can present a tidier alternative to birds, and they eat flies, especially gnats that fly at dusk and dawn. You can attract bats to your barn by placing bat boxes on the south side of a building.


Feed-throughs work by preventing flies from hatching in manure. You add the feed-through product to the horse’s feed. The product passes through the horse’s system into the droppings, where the product prevents fly larvae and pupa from developing there. Feed-throughs are totally safe and are very easy to use.

Unfortunately, feed-throughs can kill some beneficial microorganisms and will only be effective if all the horses in your yard are dosed. You’ll need to feed the product to your horses every day from early spring to late fall.

Manes and tails

Your horse’s mane and tail provide fantastic natural fly deterrents! A group of horses standing together and swishing their tails makes it extremely difficult for biting flies to settle and do their worst. Also, a long forelock can be super-effective at preventing flies from settling around your horse’s eyes.

So, resign yourself to the task of plaiting up for shows, and allow your horse’s mane, forelock, and tail to grow naturally so that your equine has his own built-in defense against flies.

In conclusion

You can take lots of positive steps to prevent flies from ruining your summer riding this year!

Remove fly attractants, such as manure, standing water, and garbage from yards and fields, and invest in some good-quality horse clothing and insect repellents. If flies are a menace in your barn, try investing in a powerful fan to keep these poor flyers at bay.

Do you have any great tips for keeping flies away from your horse and yard? If you do, we’d love to hear them! Share with us in the comments box below.

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