What Do Bots Do to Horses?

Last Updated on May 30, 2022

When warmer temperatures come along so do bots. So, what do bots do to horses? These nasty bugs can cause quite the problem for unsuspecting horses.

During hot summer days, bot flies can be a source of constant irritation for horses. Though small, these pests can affect your horse’s performance and overall wellbeing. Fortunately, there are ways to treat, manage and prevent these unpleasant bugs from bothering your horses.

What Are Bots? – What Do Bots Do to Horses?

Horse bots, also known as Gasterophilus flies, are honey bee-sized flies that fly around horses, laying their eggs on a horse’s coat. Though they do not pest or sting, they quickly dart around horses, which can cause horses to injure themselves trying to flee from them.

There are three types of horse bots: the common bot (Gasterophilus intestinalis), the throat bot (G. nasalis) and lastly the nose bot (G. haemorrhoidalis). They are considered a type of parasite and are common all throughout the world.

Bot flies are active during the warm months of the year and generally don’t disappear until the first frost. They generally come in abundance, causing annoyance to your horse.

What Are Bots

What Do Bots Do to Horses?

Bot flies have three life stages that begin with laying their eggs on a horse. They generally lay their eggs on horses anytime from late summer to early fall.

The common bot generally lays its eggs on the legs of horses, along with their flanks and manes. Throat bots will attach their eggs to the long hairs underneath the jaw of horses. Nose bots will lay their eggs on the lower and upper lips of a horse.

The eggs of the bot fly are small, often ranging in color from yellow to gray. After the eggs are attached to the hair, horses will generally bite or lick them. The eggs generally hatch after a two to five day incubation period and are generally stimulated by the warmth and moisture of a horse’s tongue.

At this point, the larvae either make their way into a horse’s mouth or are taken in unknowingly from a horse biting or liking itself. From there, they will spend about three weeks in the soft tissue of the lips, gums, or tongue. After that, they make their way to the stomach or small intestine of the horse where they use their sharp mouth hooks to attach to the lining of the organ.

They will spend around seven months in the stomach or small intestine before leaving the horse via manure. After that, they enter the soil and pupate, emerging as adults in anywhere from two weeks to two months.

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In most cases, bots will generally not cause any harm to horses. However, while inside the horse, bots can cause damage the lining of the stomach or small intestine, interfere with digestion, and cause other gastrointestinal disorders. In severe infestations, they can cause colic, weight loss, ulcers, poor appetite, and abdominal pain.

Signs Of Bots In Horses – What Do Bots Do to Horses?

The first signs of bots you will see in horses are the eggs on their hair. Though they are relatively small, they are generally still noticeable, especially when the eggs are yellow. The eggs are normally found in clusters in different spots on the horse.

You may notice your horse excessively biting or liking itself when the larvae have just hatched. In some cases, a horse may rub its face or bite strange objects to relieve the irritation of the larvae in the mouth. If a horse ingests the larvae of bot flies, there is a good chance that you will not notice.

In more serious cases, a horse may colic, have a loss of appetite or show signs of other digestion problems. In addition, they may develop ulcers as a result of the larvae.

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How To Treat Bots? – What Do Bots Do to Horses?

The best way to deal with bots is to regularly de-worm your horse. The use of de-wormer can remove bots from your horse. In more serious cases, your veterinarian may come up with a specialized plan for your horse’s individual needs.

If you notice bot eggs on your horse’s coat, you can use a bot knife or porous fiberglass bot block to remove the eggs. These tools will effectively remove the sticky eggs from the horse without hurting the horse. You can also sponge the area where the eggs are with warm water to help remove them.

How To Prevent Bots In Horses – What Do Bots Do to Horses?

No matter where you live, bots will likely affect your horse at one point or another. Though you can’t always prevent your horse from getting them. There are steps you can take to reduce the chances of your horse getting them.

Spraying your horse with fly spray and using a fly sheet can help reduce the chances of bots. In addition, fly boots and a fly mask can also help protect a horse. Removing manure from pastures on a regular basis can also help reduce the chances of reinfection.

Dealing With Bots In Horses

Bots are a common parasite horses deal with. Though they are generally harmless, they can cause problems such as colic, ulcers, loss of appetite, abdominal pain and other digestive issues.

Do you have any questions regarding what do bots do to horses? If so, please ask any questions regarding bots in horses in the comments.


How Do You Know if Your Horse Has Bots?

You may notice bot eggs on horses as they are yellow to gray in appearance and can be found on the legs, jaw, flank, mane and lips. If the eggs have hatched to larvae, you may notice your horse biting and licking more as well as rubbing their mouth. Horses may also colic, develop ulcers, show signs of appetite loss and experience other digestive problems.

What Do Bots Look Like in Horse Manure?

Bots are large, ugly and can appear quite alarming in manure. They are generally brown to pink in color when found in manure.

What Kills Bots on Horses?

The best way to kill bots is to remove them with a bot knife or a porous fiberglass bot block. Once inside the horse, de-wormer such as ivermectin or moxidectin can be used to eliminate bots.

How Do I Stop My Horse From Getting Bots?

You can help prevent bots by using fly spray and dressing your horse in a fly sheet, fly mask and fly boots. If you see bots, remove them and be sure to regularly de-worm your horse.