Adult warble flies are large, hairy and bumblebee-like and brown, orange or yellow in color.

The eggs hatch within a week and penetrate the skin, where they migrate throughout the connective tissues (H. bovis) or to the esophagus (H. lineatum).

They remain under the skin, and when destroyed by pressure, the larvae can cause large purulent swellings, or anaphylaxis.

The migrating larvae can cause damage to meat, as the tunnels they make in the muscle fill with a substance known as "butcher's jelly".

From the 1980s, the preventive treatment is easier, by subcutaneous use of ivermectin, but the warble fly remains present in North Africa.