Mydas flies are true flies belonging to order Diptera and family mydidae. While the number of species classified within mydidae is fewer than 400 species, this family of insects occurs worldwide.
Members of this family are commonly referred to as mydids. Upwards of 50 species can be found in the Pacific Northwest.
Most mydid species are strikingly handsome, elongate flies that are of medium to large size. Adult mydids occupy a wide variety of habitats but they are more commonly seen in open country.
They are fond of hot, sandy habitats and can be found resting on bare ground. Females plunge their abdomen into the ground to lay eggs.
Compared to the other legs, the hind pair of legs of a mydas fly is longer and stouter. The hind femur is enlarged and bears numerous spines on the lower surface. The hind tibia has an apical spur or bristles.
While the information on the feeding habits of the adult stage is sparse, the larvae are known to be effective soil-dwelling predators. They have well-developed mouthparts to prey on other soil-dwelling insect larvae, especially on Coleoptera beetle larvae, including white grub worms and other larvae of beetles.