Build A No-Fly-Zone

Bugs are more than just a nuisance! From skin issues to serious diseases, they can lead to a variety of health challenges for your horse. Here, you’ll learn more about the flies that are bothering your horse and find out what problems they can cause.

Different insects require different strategies to combat them, so it’s important to understand which insects are bugging your horse before you put together your plan of attack. The common insects you might see around your farm include:

House Flies

The most common fly you’ll see around horses is the non-biting House Fly, which reproduces mostly in manure. You’ll find these flies going for the moisture in the eyes, but they can be found anywhere on your horse.

Stable Flies

The second most common fly around horses (and the most bothersome) is the Biting Stable Fly. These are blood feeders, and you’ll find them on the forelegs and flanks of your horse, in particular. They can reproduce in spoiled vegetative matter, old mucky compost, and grass clippings as well as manure.


Mosquitoes are small insects that, like the Biting Stable Fly, are blood feeders. In addition to leaving irritating bites on your horse, mosquitoes can transmit several diseases to horses, including Equine encephalitis and West Nile Virus.


Ticks are blood-sucking eight-legged arachnids that hitch on to your horse to feed. You’ll commonly find them attached to your horse’s legs or chest, but they could be anywhere on his body. Besides irritating your horse when they bite and latch on, they can transmit a variety of serious diseases, including Lyme disease.

Biting Midges

Biting Midges are tiny flies that are also called “no-see-ums.” Another blood-sucking bug, they typically bite horses along the top-line or along the belly. Some horses are particularly sensitive to their bites and develop an allergic reaction known as “Sweet Itch.”


Chiggers, which are the larval form of a specific species of mites, burrow into your horse’s skin and create small, itchy bumps. You’ll most commonly find their bites on your horse’s head, chest, and neck.

Bot Flies

Bot flies are troublesome because they lay small, sticky yellow eggs on your horses haircoat, typically on the front legs, chest, shoulders, armpit, and mane. Bot eggs can be licked by the horse and hatch in their mouths fairly soon after they’re deposited, which can lead to an internal parasite infestation. If you live in area where bot flies are a problem, it’s important to remove eggs from your horse daily with a tool like a bot knife to prevent your horse from ingesting them

Allergies & Skin Issues

An allergy is an exaggerated response from the immune system to a substance in the environment, called an allergen. Allergic reactions are common in horses, and horses can develop allergies from a wide variety of things in their environment, including insects such as black flies, horn flies, and stable flies. Hives and intense itching of the skin, as well as coughing and nasal discharge, are the most frequent displays of allergies in horses.


Hives, also known as urticaria, are fluid-filled, raised swellings or “wheals” on a horse’s skin. These bumps or plaque-like eruptions are generally round in shape and flat-topped, ranging from ½-inch in diameter to as large as 8 inches wide. Hives can be caused by many things, including bug bites.

Sweet Itch

“Sweet Itch,” also known as “summer itch” or summer seasonal recurrent dermatitis (SSRD), is an allergic reaction to the Culicoides biting midge or “no-see-um” gnat. The classic signs of “sweet itch” are a horse that becomes very itchy in the spring, often to the point of rubbing out its mane and tail hair. In addition to this “buzzed mane” and “rat tail” appearance, there may be a pattern of skin irritation all along the topline: from head and face, to neck and withers, to back and rump. 

Summer Sores

“Summer Sores” or “Fly Sores” is a seasonal skin disease in horses referred to by veterinarians as Cutaneous Habronemiasis. are characterized by one or more open and draining nodules and are typically found on the legs, inner corner of the eyes, and moist areas, especially where the skin has undergone injury or irritation. They are the result of an interruption in the normal life cycle of the stomach worm. Instead of Habronema and Draschia larvae passing into the manure, being ingested by fly larvae, then deposited on the horse’s lips to be swallowed which completes the usual cycle, flies deposit the stomach worm larvae on other parts of the horse’s body, leading to a severe local reaction that is often itchy.

Insect & Tick-Bornes Diseases

Lyme Disease

Lyme Disease is a bacterial infection that is spread by the deer tick, or blacklegged tick. It is most prevalent in New England plus the surrounding states Pennsylvania, New York, New Jersey, Maryland, and Virginia, as well as the upper Midwest. In horses, clinical signs of Lyme Disease are vague, and can include sporadic or shifting lameness, swollen joints, fever, a hypersensitivity to being touched, poor performance, and more.

Equine Encephalitis

Eastern and Western Encephalitis (known as EEE and WEE) are viral infections of the brain and spinal cord in horses that are transmitted by mosquitoes. Like many infections, EEE and WEE initially cause listlessness, lack of appetite, and fever, but within a day, a horse with either disease will show neurological signs such as changes in behavior, incoordination, muscle twitches, and more.

West Nile Virus

West Nile virus is transmitted through mosquitoes, and can cause encephalitis, or an inflammation of the brain and spinal cord. The clinical signs of this disease in horses include fever, incoordination and stumbling, weakness, and more.

Find Solutions For Every Area on Your Farm

When it comes to battling the bugs, it’s important to have a barn-wide system that has every area on your farm covered. Read on to learn about the different types of fly control to use where so you can create the ultimate plan of attack for your farm.

Manure Pile

The best way to keep the fly population on your farm in check is by making sure larvae can’t mature into adult flies. That’s why your insect control plan starts at the manure pile, which serves as a breeding ground for flies. These tiny, beneficial bugs stop adult pest flies from developing by feeding upon and breeding within the developing (pupal) stages of manure breeding flies.

Feed Room

Your next step is to help your horse defend himself from the inside. A daily insect control supplement is the smartest way to help ensure that your horse has what he needs to build his own personal no-fly zone.

How Insect Control Supplements Work

There are two main types of insect control products to choose from: EPA-approved insect growth regulators, which help reduce the population (but are most effective when fed to all horses on the property) and insect defense supplements, which make your horse unappealing to biting bugs, and work well even if you’re the only one feeding it.

If you’re looking to band together with your barn mates and start all of the horses on the property on an insect control product, you’ll want to consider choosing an insect growth regulator. Formulas in this category are feed-through larvacides that inhibit the development of house and stable flies. They provide targeted ingredients such as cyromazine, which passes safely through the horse’s system to affect the fly larvae in manure.

If everyone in your barn isn’t on board, pick an insect defense supplement than can help give your horse his own personal no-fly zone. Formulas in this category provide key ingredients like garlic, apple cider vinegar, and brewer’s yeast to help discourage insects from biting your horse. Even if you’re giving your horse an insect growth regulator, this type of formula is a great addition to your program, too, because it can help protect your horse from bugs that might migrate from nearby barns.

Key Ingredients To Look For In Insect Defense Supplements

Garlic, apple cider vinegar, and brewer’s yeast: These aromatic (“smelly”) ingredients make your horse unappealing to biting insects. (But, contrary to popular belief, they won’t make your horse smell like an Italian restaurant-most riders don’t even notice a difference!)

Diatomaceous Earth: This whitish powder is made up of the fossilized remains of diatoms, a type of prehistoric, hard-shelled algae. While totally harmless to your horse, once passed in the manure, the microscopic particles have sharp edges that are said to penetrate the outer covering of worms and insects, causing dehydration and death, so they can help stop larvae from developing into adult flies.

Key Ingredients to Look for in Insect Growth Regulators

Diflurobenzuron and cyromazine: These insecticides act as insect growth regulators. They safely pass through your horse’s GI tract with no effects on your horse, and they go to work in the manure. Both ingredients are proven to inhibit the development of larvae into adult flies, reducing the population of flies around your barn.

What to Expect from Insect Control Supplements

Insect defense supplements take time to reach their full benefit, generally about 4-6 weeks. It’s possible that your horse may act comfortable and happy during turnout and your rides after the first few weeks, but if not, that’s ok, it may take a bit more time! Keep an eye on your horse over the first several weeks for how he looks and feels in spite of the bugs.

As with insect defense supplements, it’s best to start the horses at your barn on an insect growth regulator a few weeks before flies appear in your area. Since it takes 4-6 weeks for the existing adult fly population to die off, you should start to notice fewer flies buzzing around after you’ve been giving the product for a few weeks.

Fly Spray & Repellents

No one wants their horse to spend his entire time in turnout stomping and swishing his tail! Applying fly spray before your horse goes outside is a smart way to help give him the protection he needs to beat the bugs.

How Fly Spray & Repellents Work

Fly sprays and repellents can work in three different ways. First, they can act as insecticides, which means that they’re able to kill insects. Next, they can repel insects. This means that they’ll discourage flies from landing on your horse but won’t actually kill them. Finally, they can confuse flies and prevent them from even finding your horse.

But how do you know which way the fly spray you’re looking at will work? The ingredients, of course! If you’re looking for an insecticide, choose a fly spray that contains permethrin, pyrethroids, and/or pyrethrins. If you’re looking for a plant-based formula that repels insects, choose one with ingredients such as peppermint, geraniol, and citronella. If you want to try a formula that confuses insects, look for one that contains fatty acids such as octanoic acid, nonanoic acid, and decanoic acid.

How to Choose the Right Fly Spray & Repellent for Your Horse

When you’re choosing a fly repellent for your horse, the first question that you should ask is, “What form do I want it to come in?” That’s because fly repellents come in a variety of forms and sizes – from sprays to roll-ons to concentrates.

Fly spray is the most common form, and you can use it to mist your horse’s body. Most fly sprays come either in a spray bottle or in a concentrate that you dilute, which is generally the most economical solution. Roll-ons are a good way to apply repellent around more sensitive areas, like the face, while ointments are a great way to keep bugs off of wounds or out of your horse’s ears.

Once you’ve narrowed down your options by choosing the right form for your situation, you’ll want to consider the following benefits:

Long-Lasting: If you’re not going to be able to spray your horse every day, look for a fly spray that’s designed to last. While some fly sprays need to be applied daily, others may stay active for as long as 17 days!

Sweat-Resistant: If your horse spends his summers sweating, you don’t want him to sweat that fly spray right off! Choose a fly spray with a conditioner that binds to the hair shaft if you want your horse’s fly spray application to last through hot days in turnout and summer rides.

Sun Protection: If providing your horse with sun protection is one of your key concerns, you’ll be happy to know that many fly sprays also contain sunscreen. You’ll see “UV protection,” “UPF,” or “sunscreen” included on the label and in the product descriptions for fly sprays that contain sun protection.

Plant-Based: Look for a fly spray with ingredients such as peppermint, geraniol, and citronella if you’d prefer to take a plant-based approach rather an insecticide-based approach to fly control.

Designed For Horse And Rider: Some fly sprays should only be used on your horse, while other fly sprays are designed to be used by both horse and rider. If you want to be able to use your horse’s fly spray on yourself, too, be sure to check the instructions on the label of the fly spray you’re interested in.

Stay tuned next month for part II and learn how to complete your No-Fly-Zone!

Courtesy of SmartPak