The Botfly lays its eggs on the forelimbs, chest and head regions of horses between May and October and these can be seen as small yellow dots in the horse's coat.

The Licking and biting of the horse stimulates the bot eggs to hatch and the larvae then burrow into the mucous membranes of lips, gums, cheeks and tongue of the horse.

the larvae incubate for 3-4 weeks before migrating to the stomach where they grow and attach themselves to the stomach wall of the horse.

Large quantities of bot eggs in the stomach can cause loss of condition, a dry coat, increased temperature, restlessness, kicking at the belly and lack of appetite.

This may coarse intermittent diarrhoea or constipation. The larvae can cause gastritis, stomach ulcers and in severe cases perforation of the stomach causing fatal peritonitis.