Warble Fly

Warble Fly

Words / Carrie Hambach

Kingdom: Animalia

Phylum: Arthropoda

Class: Insecta

Order: Diptera

Family: Oestridae

Genus: Hypoderma

The warble fly (Hypoderma tarandi) is a pest to caribou herds throughout their range in Alaska. Anyone who has hunted or gone sightseeing for caribou has inevitably noticed the numerous lumps along their backs. These lumps, also known as warbles, are the result of warble fly larvae imbedded under the caribou’s skin. 


Beginning in late July, adult warble flies deposit their eggs on the hair along the legs and stomach of the caribou. The eggs then hatch into larvae and penetrate the skin. For the next seven to nine months the larvae will travel along the subcutaneous layer until it reaches the caribou’s back to mature. Once the larvae mature and the conditions are favorable, the larvae exit the skin and drop to the ground to pupate.


A single caribou can host anywhere between one to a thousand warbles. This greatly reduces the caribou hide and meat. However, among some Inuit, warble larvae are thought to be a fortunate find as it is considered a delicacy.