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Why Do Horses Attract Flies? Number 2 May Surprise You

Last updated: June 11, 2021

By: Miles HenryFact Checked

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In South Louisiana, mosquitoes are everywhere, but if you have horses, you also have flies. My grandson asked me about this phenomenon; he wanted to know why flies follow horses wherever they go.

Flies feed on large mammals that are dark, warm, and move around a lot; in other words, horses. Horseflies sustain themselves on the endless supply of horse blood, and fresh manure found in barns is an ideal breeding ground for them.

Horseflies, unlike houseflies, are larger and comparatively more harmful. Just like houseflies are common among households, horseflies are prevalent around horses and their barn.


1. Flies like moisture and humidity.

Do you own a stable? Or are you an owner of the horse? Well, you know about the horseflies then. Because horses and horseflies seem like a package, but instead of buying one, get one free, you get tons and tons of flies.

We live in South Louisiana, which has a lot of moisture and humidity. Because of this, we have an ongoing battle against horseflies. In the picture above and the one further down, you can see some of the steps we take to protect our horses, multiple fans in the stalls, fly sprays and fly paper.

They are mostly found in moist habitats, but their favorite stomping ground is undoubtedly near horses. Heat and humidity seem to be their preferred climate. Simultaneously, they are less likely to be found during a dry and cold period.

Horseflies to human beings aren’t a significant threat apart from a rash of redness, but they can indeed cause deadly diseases to the horses. No one would know a horsefly better than the horse owner and the damage they bring along themselves.

2. Horseflies get protein from horses.

Female horseflies need protein for the development of their eggs, which they get by sucking blood, and it’s not only horses they get it from. Horseflies feed on most large mammals, cattle, and horses, to name a few.

What most attracts them to their target is warmth and movement, which horses typically provide both. Horseflies will thrive on horses and not only do they get protein from their blood but also from the moist material around horses eyes.

Another reason horseflies live near horses is because they reproduce in fresh horse manure, which, of course, is moist and warm. Horseflies are attracted to dark horses more than the light-colored. Their favorite target is a dark, warm, and moving object.

Are flies irritating?

Flies are pests, in the literal sense, they burrow in horses ears, bite them, and buzz around their eyes. Even when their not in a horses sensitive area, their sheer numbers are often annoying a horse.

The sheer number of flies leads some to swish their tails non stop to rid the insects from their sides and underbelly. The horsefly is incredibly irritating for the horses. It causes a significant level of discomfort, especially when they sink their cutting teeth into the animal’s flesh to draw blood.

Are Horseflies Harmful?

Insects, parasites, pests, they are all harmful. We all know horseflies bite, but interestingly it’s only the females; males just irritate. Females need to supplement their protein during reproduction; hence they bite and retrieve it from mammals.

The bite can cause cuts on the flesh, which can be extremely painful. The puncture can also cause the particular area to be reddened and swollen, leaving a bump on the horse’s skin, visible from afar. The open wound from a bite is vulnerable to infection

Does The Horsefly Transmit Disease?

Horseflies can and do transmit disease. In fact, there is a high chance of a horse getting sick because of disease transmission from a horsefly bite.

Furthermore, due to female horsefly bites, there is an increased risk of blood-borne diseases in the horses and some of these diseases can be fatal. Consultation with a vet is often essential to the horse’s well-being.

However, most horsefly bite brings from few to no harm to the animal. Equine infection: Equine Infectious Anemia (EIA) is a disease that is easily spread from horse to horse by horseflies.

It is a fatal disease, and once a horse contracts EIA, the animal is a carrier for life and must be quarantined. Apart from it, they originate many other diseases like swamp fever among horses.


How To Prevent Flies?

Due to the high risks of diseases and discomfort caused by the horsefly, preventive measures become necessary for animal well-being. There is plenty of actions that can be taken to keep the flies away.

 Manure Management

Every barn needs a plan to dispose of manure away from the barn. Stalls should be mucked out daily, and the waste put in a wheelbarrow and disposed of in a location far away from the barn.

Once a month, we have the waste material picked up and hauled off. Some people use manure for fertilizer in our community, so they pick it up for free.

You may want to check your area to see if you can locate someone to do the same for you. How frequent you need to haul your debris depends on your location and the number of horses you house.


These bloodsuckers we’re trying to eradicate typically flourish around fresh manure, so if you have a horse in a small paddock, try spreading it to dry it out quickly; this helps.

But, not only must you take control of manure, but you also need to eliminate open trash piles. To effectively control insects, step one is to keep your barn clean, which includes proper manure management and garbage management.

Don’t leave trash around your barn, have a can with a lid, and keep it closed, and when the can is full, empty it, never let it overflow.

Fly Traps

Various traps can seduce the flies, which is an easy way to catch some of them. A container filled with any attractant can perform pretty well. Some of my friends fill zip lock bags with sugar water and hang them in various barn locations.

There are many different styles of commercial traps, and they vary significantly in design and price. For example, the Bite-Lite H-Trap Professional Horse Fly Control System is a highly advanced fly control system that sells on Amazon for over $300.

At the other end of the spectrum is the RESCUE! Outdoor Disposable Hanging Fly Trap sells for $11, and there are many in between these pr ranges.

I suggest you read reviews about the products you are interested in to find out which suits your needs best. Here is a link to the reviews for Rescue! Outdoor Disposable Hangin Fly Trap, there are over 11,000 customer reviews.

Horse Protection Tools

Certain on-horse accessories can prove to be helpful. Fly masks cover the area of eyes and an upper face of the horse and shield the horseflies.

You can buy fly masks for your horse with or with ear protection. I reviewed many different masks and chose my three favorites with ear protection in an article you can read here.

Similarly, fly sheets and boots can protect horses from aggravating insects. I wrote a helpful article on the effectiveness of fly boots that you can read by clicking here. If you’re interested in reading why horses wear blankets, even in the summer, please click here.

Fly Predators

This one is really effective in the long run. Fly predators are small insects that eat fly offspring. They don’t bother humans or aggravate horses. Their scientific names are muscidifurax raptorellus, Spalangia cameroni, and Muscidifurax zaraptor.

When these predators are left near horse manure, they knock out large portions of the fly family and significantly reduce horseflies’ future growth.

Horsefly predators are commercially sold. I have never tried them but did visit this site and read about their effectiveness. They make them sound intriguing, and it may be something worth giving a shot.

They are released in the reproducing period around the moist surroundings like fresh manure or any other decomposing happenings. This is where horseflies lay eggs, and fly predators eat them in their initial stages.

Solitude IGR

Solitude IGR is a feed supplement that is mixed with your horse’s daily rations. Once its ingested, it discourages the growth of pests around barns by reducing fly reproduction in manure. According to horse owners, this is yielded excellent results.

It’s sold on Amazon and has a customer rating of 4.6 out of 5 stars. Click here to read what the people who’ve used the product have to say.


Sprays/ Repellent

Spray repellants are useful, and we use many of them; I find a couple works well. Endure seems to stay on last a little longer than other brands. But most are effective and need to be often applied, especially if there are many insects near your animal.

South Louisiana has loads of mosquitoes and flies, and insect repellent spray is in everyone’s horse trailer and tack room. Before you start spraying your horse all over its body, first perform a small patch test on the horse’s skin to ensure it’s not allergic to the spray. Here is a link to a couple of the more popular fly sprays:


Roll-on insect repellents are typically used on sensitive areas of horses’ face and head like around the eyes and ears. They are effective in keeping insects off these regions without subjecting your horse’s face to sprays.

These measures can be taken to protect the horses for the horseflies. Apart from it, a simple and easy way out is to leave the horse in a dark shady stable that’s cool and dry because flies are inactive in darkness.

But again, horses do need sunlight and fresh air as well, just like human beings. Hence the ways mentioned above can prove to be really useful.

YouTube video


Horseflies are difficult to escape from, especially for horses. So the only way is to live with them and get used to it while taking preventive measures that reduce the damage, but you’ll never completely eradicate these aggravating insects.


Do horsefly mask and boots work?

Some horsefly masks and boots work really well, while others are difficult to put on and ineffective. If you want to learn more about masks and boots, check out this article: Do Horse Fly Masks and Fly Boots Work? What Ones Are Best?

Can you ride a horse with a fly mask?

You can ride your horse with a fly mask so long as it doesn’t obscure its vision. Some masks are designed better than others for riding. If you need more information about riding with fly masks, read this article: Can You Ride a Horse With Fly Mask On? Plus 5 Horsefly Tips

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How helpful did you find this information regarding horses and horseflies? Don’t forget to share your opinion in the comment section below!