Gasterophilus Intestinalis is a species of parasitic fly that is commonly known as the botfly. It is a significant parasite of horses and burrows into the walls of the stomach and intestines, which can lead to serious health complications. There are several synonyms for Gasterophilus Intestinalis, including the common horse botfly, intestinal botfly, and stomach botfly. The botfly has a life cycle that involves several stages of development, which occur within the horse's digestive system. These stages include eggs being laid on the horse's hair, the larvae hatching and then entering the horse's mouth when they lick themselves and the development of larvae in the horse's digestive system.