Bots

Bots strictly speaking are not worms, but insect larvae of Horse Bot Flies. They are the most common parasite of the stomach affecting horses of any age. 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 cause ulcers in the stomach wall even penetrating the wall with fatal results. It 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 manure. They then pupate underground until the adult flies emerge in the summer months and begin to lay their eggs.  The first hard frost kills off the adult flies so no re-infection will take place over the winter, resulting in targeted treatment following the first hard frost.