How to Prevent + Treat Bot Fly Infections in Your Horse

A woman cleaning a horse's nose.

Bot flies are nasty little things that many horse owners are likely acquainted with, whether they want to be or not. If you’ve never heard of a botfly or a botfly infection don’t worry, we’ve got you covered. Today we will be breaking down what a botfly is, its infection, how to identify it, and how to treat it. This way you can be ready for if and when your horse gets infected.

What is a Botfly/Botfly Infection

So, what exactly is a botfly? Botflies are rather chunky little creatures that can be found throughout North America and the northern regions of Mexico. They have rounded heads and often have a fuzzy bee-like appearance. Believe it or not, adult bot flies are rarely seen. The most commonly seen form of botfly is the kind that is the most terrifying, their larva. These larvae are small pudgy little grubs that live in the tissue of animals as parasites.

A close up of a botfly.

These things are pretty easy to confuse for bees at first glance. Image courtesy of Bugguide.

The Botfly Infection Process.

The Botfly itself does not actually harm the horse by biting or stinging it. The danger of the botfly comes from its ability to infest the horse with its parasitic larvae. Botflies tend to lay their eggs on the skin's outer layer. The most common places botflies lay their eggs are on the knees, inner legs, belly, around the neck, and around the nose of a horse.

Botfly eggs can be identified by their small size and yellowish-orange color. They can be much easier to notice on horses that have darker skin colors. The aim of the botfly when laying its eggs in the location they’ve chosen is to get the horse to ingest the eggs. This is why they lay them in locations that the horse will be able to pick at and reach with its mouth.

Once the horse has ingested the botfly larvae, the larvae will make their way to the horse’s stomach and attach themselves to the lining of the horse’s stomach. This process of digging into the horse’s stomach causes all kinds of problems and discomfort for your horse. Issues like:

All of which can potentially lead to life-threatening conditions.

After living in the horse’s stomach as a parasite for 8 to 10 months, the larvae will have matured and will be ready to pass on into the horse’s manure. From there they will live in the ground until they mature into fully grown botflies and head out to repeat the cycle anew. In truth, pretty messed up stuff. So, how can we tell if our horse has been infected with botflies?

A horse eating in a field.

Botflies are most active around the warm months of the year. Image courtesy of Equinewellnessmagazine.

How to Tell if Your Horse is Infected with Botflies?

A good place to start looking for symptoms of botfly infection is by watching to see if your horse is constantly licking or nipping at spots on its legs or stomach. These could be signs of clumps of eggs in that location that are irritating your horse.

Another sign your horse may be infected is if it suddenly starts biting strange objects that it has never bitten before, or if it starts to rub its mouth or face against objects. This could be a sign that your horse is trying to deal with the irritation going on in its mouth thanks to the botfly eggs.

The last symptom to keep an eye out for is poor appetite or abdominal pain. If your horse suddenly stops eating or begins eating much less than he/she usually does, then that may be a sign of botfly infection in the stomach. 

Two horses comforting each other.

As horse owners, it’s our job to keep them happy and healthy. Paying attention and being proactive is the best way to accomplish that goal. Image courtesy of Blog.Mystart.

How to Treat a Bot Fly Infection

In truth, diagnosing botfly infections can be really tricky. If you suspect that your horse may be suffering from a botfly infection, your first course of action should be to have your local vet take a look at your horse and diagnose the problem. If your horse is suffering from a botfly infection there really isn’t much that can be done to treat them other than giving your horse a prescribed dewormer. The best way of dealing with a botfly infection is to try and prevent it from occurring in the first place.

How to Prevent Botfly Infections

There are a few ways you can prevent botfly infections from occurring in the first place. First up is proper grooming. Grooming your horse on a regular basis, especially during the warm months can allow you to remove botfly eggs from your horse’s hair and skin before he/she has a chance to ingest them. During the grooming process, it may be a good idea to use horse-safe insecticide alongside warm water to help wash away any botfly eggs. Insecticides can also be applied directly to areas of the skin that have been identified as botfly areas.

Another great option is the regular application of a horse dewormer. While there are plenty of over-the-counter options available to horse owners, we recommend you speak with your horse's veterinarian and receive a dewormer that is the best fit for your horse’s health conditions. Most dewormers will remove botfly larvae from your horse’s stomach along with many other worms and parasites that may have made their house and home in your horse’s gut. 

Applying dewormer on a regular basis can help prevent your horse from suffering for those 8 to 10 months before the larvae move on to the horse’s manure, and will help catch the larvae early before they can cause too many health problems.

The last recommended preventive measure is to check your horse’s manure regularly for pupae botflies. If you can catch and destroy the botflies before they have a chance to mature into adults, you can effectively break the cycle and reduce the number of botflies that will be bothering your horse in the future.

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