Bots are strictly speaking not worms, but insect larvae of horse bot flies.
They are the most common parasite of the stomach. Depending on the species,
and there are several different types, the eggs are laid on the legs or
around the muzzle of your horse.
Female adult bot flies resemble bees and are often a
considerable annoyance to the horse when laying eggs.
After hatching, the larvae get into the horses mouth
and burrow into the base of the tongue and below the gum line. After
approximately a month in the mouth, during which they double in size, the
bot larvae move on and attach themselves to the stomach lining where they
develop into the full grown bots.
Bots can give rise to ulcers in the stomach wall and can
even penetrate the wall with fatal results. lt has recently been
discovered that they will also attach themselves in clumps to the first part
of the intestines causing similar problems. This poses a special danger for
small breeds and to young horses whose stomach and intestines are likely to
be thinner and more easily damaged.
Left untreated bots remain inside the horse until the
spring when they pass out in the droppings. They then pupate underground
until the adult flies emerge in the summer months and begin to lay their
eggs: and the whole cycle starts again.
The first hard frost kills off the
adult flies, no re-infection will take place over the winter.
Bots can affect horses of any age.
