Females will lay fertilized eggs on or around the burrow or scrape of a rabbit. These eggs are picked up by the rabbit in a variety of ways: catching its fur as it passes, possibly inhaled or maybe even swallowed. The egg migrates through the internal body of the rabbit and settles on an area just under the skin. This area could be on the neck, throat, stomach or appendages. Once settled, the egg hatches internally and the larva (maggot) grows. A large tumor-like bump forms. This bump is called a warble. A hole is created in the warble to allow the maggot to breathe (called a warble hole). The maggot will grow larger and eventually push itself out of the animal through the warble hole and fall to the ground. There, it will encase itself and pupate. Once it has finished pupating, it emerges as a flying adult.
Rabbit Bot Fly eggs cannot select which kind of animal it encounters, so there are cases where small animals like squirrels and rodents as well as house pets are found with warbles. This parasitic fly does not kill its host and only resides inside it for a short time. Veterinarians can remove the maggot in a pet and treat the warble hole so it heals properly and does not create an infection.