Woodrat Bot Fly (Cuterebra americana)
Detailing the physical features, habits, territorial reach and other identifying qualities of the Woodrat Bot Fly.
Updated: 6/28/2016; Authored By Staff Writer; Content ©www.InsectIdentification.org
The large Woodrat Bot Fly is a terrible menace to woodland rodents and squirrels as well as domestic cats and dogs, often requiring an eventual trip to the veterinarian.
Woodrat Bot Flies are members of the the Oestridae family. These large, bee mimics do not sting, nor do they bite. This species is, however, a parasite to small mammals in the forest as well as unfortunate pets. The female fly deposits fertilized eggs around the perimeter of a den or hole occupied by a rodent or rabbit. Once the rodent passes by, it picks up an egg in its nose (sniffing around) or mouth. The egg, now inside the animal, moves to the outer body, just under the skin. This may be around the throat, stomach, legs or back. There, the egg enlarges and a tumor-like growth forms on the animal. This is called a warble. The small hole is created in the warble (warble hole) that will allow the hatched fly larva to breathe. The larva (maggot) is worm-like, plump and grows in size. When it is ready to pupate, it leaves the warble through the hole and falls to the ground. This usually leaves the animal with a large gaping wound that can easily become infected if not treated. Pets with a warble can be brought to a veterinarian, where the Woodrat Bot Fly larva may be removed and the warble hole treated so that it heals. The newly-freed larva will encase itself on the ground and pupate, emerging as a flying adult.
As a parasite, the Woodrat Bot Fly does not kill its host, but it can make it uncomfortable and even sick if not treated.