The following resources are for informational purposes
only. Please consult your vet. to determine the best
program for you & your horse in your geographical
location.
Understand and Control Botflies
Understand a bot's life cycle and learn how
it can affect your horse and how to control it.
By Jayne Pedigo
During the summer and early fall months, you may
notice the appearancs of small yellow-ish dots on your horse's
coat. These are the eggs of Gasterophilus, the botfly,
which the botfly lays on the hair shafts on the chest and
forelegs of the horse. Botflies are particularly annoying to
horses, causing them to stamp and bite at themelves.
This biting action of the horse stimulates the larvae to hatch
from the eggs and the horse then, in the course of his licking
and biting, takes the larvae into his mouth. Once in the mouth,
the larvae burrow into the cheeks and tongue of the horse, where
they remain for about three weeks. While in the mouth they do
not appear to cause any discomfort or worry the horse.
From the mouth, the small larvae migrate to the stomach, where
they develop into larger larvae. They attach themselves to the
stomach wall by their teeth. They stay in the stomach all
winter, and can cause gastritis and even perforation of the
stomach. In the spring, they release their hold and pass out in
the manure to develop into adult flies and begin the life cycle
again.
Horse owners can control the infestation of their horses by use
of a bot knife to remove the bot eggs from the hair on a daily
basis during the fly season. In addition, modern dewormers
containing ivermectin are efficient at killing the larvae that
reach the stomach. For this reason, many veterinarians advocate
the rotation of dewormers to include products containing
ivermectin, in the fall and again in the spring for maximum
efficiency.
