Gasterophilus, commonly known as botfly, is a genus of parasitic fly from the family Oestridae that affects different types of animals, especially horses, but it can also act on cows, sheep, and goats.

They have a hooked mouthpart that allows them to attach into the gastrointestinal tract of the infected animal and a rounded body that is covered with spines in rows, of which quantity varies from different species.

During this phase they look similar to drone bumble bees; They have developed a pair of wings with brown patches and a body that is covered with yellow and black hairs.

Due to the animal grooming that starts after seven days from the egg being laid,[5] the hatched larvae end up in the host mouth and tongue where they get attached for more than a month before being ingested.

After leaving, which occurs in about 3-10 weeks,(depending on the temperature)[5] the adult bot fly emerges from the pupa and starts the cycle again.