Bots are a type of intestinal parasites that are larvae of the botfly, Gasterophilus. Female botflies lay their eggs by attaching them to the hairs of the horse.
Different species lay their eggs on different parts of the horse’s body.
Botfly larvae probably cause minimal damage to the stomach but can cause damage to the lining of stomach and cause outflow obstruction.
For more information about Bots, see Stomach Bots in Horses.