Want to breed your own insects? Check out our YouTube Channel for video tutorials.

Best Fly Masks and Sheets for Horses

Posted by Critter Depot on

Table of Contents

Best Fly Masks and Sheets for Horses

best horse fly mask

Table of Contents

Why do I need a Fly Mask for my Horse?

Fly sheets and masks are an effective way to keep flies from landing on and biting your horse. There are four main types of flies that affect equines: horse flies, deer flies, stable flies, and house flies. Physical barriers, such as sheets and masks, are one way to dissuade insects from bothering your horse. Chemical barriers and environmental controls should be utilized in conjunction for the best overall defense against biting insects.

Can Flies Harm my Horse?

Insect control is a common challenge around the barn. Geography will dictate the specifics, but generally late spring through fall is “bug season.” Insects are not only a nuisance—their bites can transmit diseases and cause irritation, allergic reactions, and even infection. There is not one solution to control insects around your horses; rather, insect control should be looked at as a sum of many different parts. This can include physical barriers, such as fly sheets and masks. Chemical barriers, specifically fly spray, can be another effective measure. Environmental controls should also play a factor in your overall program. These can include cleaning schedules, manure location and removal, and property maintenance to eliminate standing water and other insect breeding grounds.

Insect 101

What insects are we referring to? In the United States, “insect control” generally means any biting creature that can affect you and your horse. The four main types of flies are horse flies, deer flies, stable flies, and house flies.

Horse flies

horse flies

Horse flies are the largest of the three fly types, ranging from 0.75-1.25 inches long1. The mouthparts are composed of tiny blades, which are used to cut a hole in the horse’s skin. Then, the fly feeds off the blood that pools in the wound. These bites are large and painful; horses may panic and attempt to run away from their attackers, which isn’t fun if you’re riding or trying to handle them when this happens. That said, it takes a few seconds for the horse fly to land and secure itself before it can bite—their size makes them slower. If you’re quick, you kill them. Generally active during the day, horse flies may respond to repellents containing DEET. However, physical barriers are most effective against this kind of fly.

Deer flies

deer fly

Deer flies are significantly smaller than horse flies, ranging from ¼ to 1/3 of an inch in length. Similar to horse flies, deer flies are also active during the day and attracted by movement, shiny surfaces, carbon dioxide, and warmth2. Most active during the summer, deer flies may respond to DEET or permethrin-based repellents. It’s important to read application instructions carefully; some repellents can be applied to horse skin but not human, or clothing/blankets but not directly to the skin. It’s interesting to note that only the female flies feed off blood; males subsist on nectar and are not harmful to livestock or people.

Stable flies

stable flies

Stable flies are the most common nuisance to horses and their owners and the smallest discussed, averaging 5-7 mm in length. Not only are they annoying, they can also carry pathogens. These flies prefer bright and sunny areas and avoid dark enclosures. They look similar to house flies, but adult stable flies have a piercing/sucking proboscis to extract blood from their host. Bites are painful and primarily found on the legs, belly, face and neck3.

House flies

house flies

House flies are the same flies you may be familiar with in other contexts. These don’t bite—they use their mouthparts to blot up liquids. It is common to see house flies around the horse’s face, especially the eyes. House flies are less irritating than the other types of flies mentioned, but still a risk—they carry a range of diseases including intestinal parasites and eye infections. House flies like moist, decaying organic matter; manure, wet shavings, and garbage are all attractive. 

horse with fly in eye

While this article primarily focuses on flies, insect control often includes mosquitoes and culicoides (biting midges/gnats) as well.

Fly Protection Basics

There are three main ways to control insect activity around your horses. These include:

Physical barriers.

Fly sheets, fly masks, and fly boots fall under this category. It’s important to check for fit; too snug and these solutions can cause hair loss or even sores. A fit that is too loose can create a safety issue.

Fly Sheets

Fly sheets are lightweight blankets that cover the horse and shield it from insects. An added benefit to sheets is protection from the sun, which keeps the coat from getting bleached out. Fly sheets should be light in color and allow for air flow so the horse doesn’t overheat. Flies are attracted to large, dark objects; light-colored fly sheets act as camouflage for your horse. Fly sheets are less common than fly masks—generally you will see them on show horses, or horses with more severe reactions to insect bites.

big fly sheet

Cost: $27 to $249. Generally, price correlates to quality; more expensive sheets will fit better and likely last longer, although that can depend on the horse. I’ve had cheap fly sheets last only a few weeks; higher quality ones can hold up for several years with proper care and maintenance.

Fly Masks

Fly masks shield the horse’s face from flies. They can come with or without ear coverings. Ear coverings can be very helpful in protecting from biting insects, especially if you clip your horse’s ears for showing. Fly masks are the most common form of fly protection.

Cost: $20 to 50

Fly Boots

horse boots

Fly boots cover the horse’s lower legs, physically shielding them from insects.

Cost: $25 and up. These are much less common to see compared to fly masks and sheets.

Chemical barriers

This would be fly spray—cost and effectiveness varies.

Insecticidal sprays generally contain pyrethrin or permethrin. These work to deter flies from landing and kill those that bite. Fly sprays can vary in price; generally, the more expensive, the longer it will last. Despite label claims, fly spray typically needs to be re-applied daily; more frequently if it rains or the horse is washed.

Endure Sweat Resistant Fly Spray is my personal favorite; it seems to last the longest. A 32 oz spray bottle runs about $20.

Repellents are typically marketed as “all natural” and use strong-smelling oils like citronella or tea tree. They hide the scent of the horse, discouraging insects from landing. Repellents are less effective than insecticidal sprays and need to be applied more frequently.

Environmental controls

This encompasses everything from manure removal and manure pit location, to removing or treating standing water, installing auto-fly-sprayers, or even biological measures such as utilizing predator wasps to target fly populations. Prices vary significantly; it is best to get local information and quotes for the most effective solutions.

Each method has its own pros and cons; you should consider all options and implement the combination that is most effective given your location, needs, and resources.


Insect control is an important topic for horse owners and stable managers. This article primarily focused on flies: horse flies, deer flies, stable flies, and house flies. The most effective measures to keep flies from biting your horse are generally a combination; a fly mask, sheet, and daily spritz of fly repellant or equine-safe insecticide works well. Addressing environmental factors to eliminate breeding grounds is also important.


Terminix: Horse Fly Bites. https://www.terminix.com/blog/education/horse-fly-bite-danger/

University of Kentucky: Entomology. https://entomology.ca.uky.edu/ef511

Equus: Head off fly problems. https://equusmagazine.com/horse-care/get-a-head-start-on-flies-14671



Leave a comment

Please note, comments must be approved before they are published