The Mydidae, or Mydas flies, are a cosmopolitan family of flies. It is a small family, with about 471 species described. They are generally large in size, including the largest known fly, Gauromydas heros. Many of the species, in addition to their large size, are mimics of stinging hymenopterans, especially wasps. Most mydids are found in arid and semiarid regions of the world, but they are also found in other habitats.

The Apioceridae, or flower-loving flies, are a small family of flies, all in the single genus Apiocera. They occur mostly in dry, sandy habitats in the deserts of North America, South America, and Australia. Other genera formerly placed in Apioceridae are now in Mydidae.