Skip to Content

6 Horsefly Facts You Need to Know? The Keys to Fly Control

Any links on this page that lead to products on Amazon are affiliate links and I earn a commission if you make a purchase. Thanks in advance – I really appreciate it!


This summer, there seem to be more horseflies in and around our barn than ever before. Watching our horses swat at these pests with their tails made me wonder what’s the most effective way to keep them off our animals.

Horseflies are attracted to movement, moisture, and carbon dioxide. To protect horses effectively, we use chemical pesticides, reduce moisture, and cover our animals. Horseflies are impossible to eliminate from a horse barn, but there are ways to decrease their numbers.

Everyone wants to rid their property and animals of horseflies, but this is an unrealistic goal. A realistic pursuit is to reduce the number of horseflies and protect horses against these unwanted insects.

6 Key horsefly facts.

Horseflies and horses typically come as packages, and some researchers believe they’ve been together since the dawn of time. So if you own a horse or intend to buy one, it’s essential to be knowledgeable of horseflies.

Picture of a horse with its ears pinned after a horsefly bit him.

1. Horseflies are attracted to movement.

Horseflies like to attack dark, moving objects. A recent study revealed how much more frequently horseflies attacked dark horses than light horses in a similar environment.

Horseflies are also fast, strong fliers capable of traveling more than 30 miles, though they generally stay in the same area. Horseflies will often congregate on paths and roads in wooded areas, waiting for victims to travel past. Horseflies are most active during daylight hours.

2. Horseflies are a global pest.

Horseflies go by many different names, but regardless of what you call them, they are in all quarters of a horse farm. They can be found all over the world except for a few islands and frigid climates.

We know they have been around since the Ancient Greeks’ times when Aeschylus blamed them for driving people mad, trying to rid themselves of these aggravating menaces. (See Aeschylus to learn more).

3. Female horseflies are the ones that bite.

Horseflies are part of the fly family Tabanidae and can be as small as a housefly or as large as a bumblebee. They have metallic or iridescent eyes that meet in the male and apart in the female. They can be either black or grey-colored. Female horse flies are nasty biting bloodsuckers.

Their mouth is designed with a skin-piercing apparatus, and two cutting blades are used to cut through flesh and lap up the exposed blood. While feasting on the blood, the fly injects an anticoagulant containing a substance to ensure the blood keeps flowing.

4. Horseflies inject bacteria when feeding.

The anticoagulant injected into the host often has contamination from other sources. These contaminations include viruses and bacteria, which spread diseases.

When a horsefly gets blood from its source, it also injects bacteria, leading to infection. These bloodsucking female horseflies can suck dangerous amounts of blood, especially when teamed up with other female horseflies.

Horseflies can negatively impact livestock; they transfer disease and can, reduce growth rates in cattle, and lower the milk output of cows. The female horse-fly needs blood to supply protein used in the production of her eggs.


5. Horseflies thrive in moist environments.

The female lays eggs in the grass in the fall, and the eggs hatch the following summer. The larvae of the horse-fly develop best in moist soil close to water.

They only live for a short amount of time, some only a few days, but it is enough time for them to be pests. To control the population of horse-flies, drain standing water, and spread oil in their breeding areas.

I’ve recently found a site that sells horsefly sprays, dewormers, shampoos, and other products at reasonable prices; click here to check it out.

6. Horseflies carry swamp fever.

For humans, a horsefly bite is painful but not usually a cause for concern; however, it can be dangerous for a horse. Horseflies carry swamp fever, and when they bite a horse, they can transmit this life-threatening disease.

A horse with swamp fever may hemorrhage and display general signs of illness. However, not all horses show signs of disease but transmit the virus to other horses (carriers).


Swamp fever is also called equine infectious anemia.

Equine infectious anemia (EIA), otherwise known as swamp fever, does not have a recommended course of treatment or vaccine. A blood test is used to confirm swamp fever; the most common test is the Coggins test.

Because of the severe consequences associated with swamp fever, you should have your horse tested at the earliest signs of the disease. A horse that has tested positive for the virus will have to enter a lifetime quarantined or euthanized.

Horses with swamp fever are quarantined.

Your property may also be subjected to isolation as well. The Equine Disease Communication Center (EDCC) is a privately run organization whose mission is to help control the outbreak of equine-related infectious diseases. Visit their site for more information about the program

Protection against horseflies.

There is no easy way to get rid of horseflies. Horse owners have fought horseflies since the horse has been domesticated. However, it is still an ongoing battle. Some helpful methods include a horsefly mask to protect the horse’s eyes and ears, fly sheets to protect the body, and the use of repellants.


A horsefly mask protects a horse’s face.

A fly mask can help protect your horse’s face from flies. It is semi-transparent, so the horse can still see and hear while wearing it. They are commonly made of black and white mesh material, and some are treated with insect repellant.

Fly masks are designed to cover the upper portion of a horse’s head (ears and eyes). They come with or without ear coverings and are secured to the horse with Velcro.

Masks are not designed for use when riding and must be removed daily and cleaned. There is a wide variety of designs to choose from, and you can check Amazon by clicking Fly Mask with Ears for current prices and styles.

Horsefly sheets protect a horse’s body from horseflies.

Horsefly sheets cover your horse’s body and are similar in design to a turnout-out blanket. They are built to allow your horse to move naturally while protecting against flies and other insects, such as fleas.

Horsefly sheets also have UV protection.

They are made of open-weave mesh. Some fly sheets are treated to shield the horse’s coat from the sun’s harmful UV rays and insects. Fly sheets can be purchased to coordinate with fly masks and fly boots.

Fly boots or fly wraps are used on the horse’s lower legs to reduce stomping and pacing caused by the aggravation of horse fly on the lower limbs. The goal is to minimize stress and stomping by your horse, which can harm a horse’s joints or loosen horseshoes. You can check here for current prices from Amazon Horse Fly Sheets.

Things for you to consider when ordering your flysheet:

  • Lighter colors are better- Horseflies like dark colors.
  • Know your horse’s activity level- If your horse is hard on equipment, then buy something durable, a cheap, lightweight model will not last.
  • Pick the right size- If you have a horse blanket that fits your horse, check to see if they make a flysheet and order from the same company. An ill-fitting flysheet will not be helpful in the long run.

Are Horsefly Sprays Effective?

When we trail ride, participants often bring various types of horsefly sprays. Watching the riders break out their sprays made me wonder how effective they are in eliminating insects.

Horsefly sprays are very effective for a limited amount of time. The best horsefly sprays will last roughly an hour. You can mix your horsefly spray or purchase a commercial brand. By combining your own, you can choose ingredients that work best for you and your horse.

Some horse owners elect to use natural ingredients to limit their horse’s exposure to harmful chemicals. Depending on the ingredients you use, a homemade mixture of horsefly spray can be as effective as a store-bought one.

Homemade horsefly sprays mask a horse’s scent.

One of the ways a horsefly identifies its target is by smell, so to be effective, a spray needs to have the capability to mask the applicant’s scent. An excellent natural source that is also readily available for this task is white vinegar and pine sol.

Pine-Sol is a useful deterrent to keep horseflies at bay; however, it can also be an irritant if sprayed directly on a horse. Only use Pine-Sol around the barn and avoid spraying on your horse.

Other useful ingredients are essential oils, such as Eucalyptus oil, peppermint oil, lemon oil, and lavender oil. These will help to confuse the fly and hopefully cause them to avoid your horse.

After you have selected ingredients to experiment with, perform a patch test on a small area of your horse to ensure it does not have a bad reaction to the spray.

Some homemade horsefly sprays are as effective as commercial brands.

An example of a simple horsefly spray: Combine 2 cups of vinegar with 1 cup of water and 1 tablespoon of Eucalyptus Oil. Mix in a spray bottle and shake well before each application. This mixture is effective and safe for most horses.

Click here to read our article for a homemade fly spray that works. If you are interested in purchasing a commercially made horsefly repellant, you can click here to check Amazon pricing. Horses Natural Fly Repellent

Do Horsefly Traps Work?

Recently I saw a curious contraption set up near a barn; it was designed to attract and trap horseflies. This apparatus looked strange, but does it catch horseflies?

Horsefly traps work. As the name suggests, a horsefly trap is a contraption designed to catch horseflies. There are many designs on the market and some DIY models as well. I would recommend using a DIY model to begin with and monitoring your success rate.

We used to hang bags of water in the barn with the tops open to catch horseflies. The bags worked pretty well; however, check this link for an ingenious design that seems to work.

If you want to go with a commercial trap, check out this Amazon link Professional Horse Fly Control System Traps Horse Flies Without Chemicals or Electricity.

horseflies, insects,flies,

Horsefly bites aren’t typically harmful to people.

A typical reaction to a horsefly bite is heat and redness in the affected area. The discoloration and heat should clear up on their own in a few days. You want to clean the affected area with soap and water and spread hydrocortisone cream to help the healing process.

If you have persistent itching, you can take an antihistamine pill. If you have any symptoms that are unusual such as pus, foul odor, and signs of infection, you need to contact a physician.

Some people have allergic reactions to horsefly bites.

There are also instances of people having allergic-type reactions to bites, such as difficulty breathing, a spreading rash, and severe pain; any of these signs also warrant seeking medical attention.

In 2013 a man died from anaphylactic shock caused by a horsefly bite. Dying from a horsefly bite is extremely rare; the man most likely had a genetic predisposition to the reaction.

To help prevent horsefly bites, wear light-colored clothing covering most of your skin and use a spray repellant. Horseflies can transmit diseases from one host to another host, similar to mosquitos.

Below is a YouTube video that provides some interesting facts about Horseflies.

Related articles: