Mydas atratus

Distinguished from robber flies (Asilidae), particularly wasp-mimicking species like Ospriocerus abdominalis or Wyliea mydas, by its elongate clubbed antennae—robber flies have short, non-clubbed antennae. The all-black coloration separates it from red-and-black patterned mimetic species. The genus Mydas is further distinguished within Mydidae by its large size and specific antennal structure.

Large-bodied fly with uniformly black coloration. Antennae are elongate and distinctly clubbed at the tips—a diagnostic feature of the family Mydidae that separates mydas flies from superficially similar robber flies (Asilidae), which possess short antennae. Body size is substantial relative to other North American flies, consistent with the genus Mydas being among the largest flies on the continent.

Documented occurrence records exist through iNaturalist, though specific range boundaries are not detailed in available sources. The genus Mydas is distributed across North America, with related species associated with various habitats including sandy areas and woodlands.

• Ospriocerus abdominalisRobber fly with similar large size and wasp-mimetic appearance, but distinguished by short antennae (vs. elongate clubbed in Mydas) and red abdominal dorsal coloration (vs. all-black in M. atratus)
• Wyliea mydasWestern robber fly with similar mimetic black-and-red coloration pattern modeled after spider wasps, but distinguished by short antennae and different color arrangement (wholly black abdomen with red wings vs. all-black in M. atratus)
• Tabanus atratusLarge black horse fly with similar common name and size, but distinguished by distinctly hooked antennae, different wing venation, and family-level characters of Tabanidae

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Bug Eric: Caught on Video: Prionyx atratus
• T.G.I.Flyday—Black horse fly (Tabanus atratus) | Beetles In The Bush
• Ospriocerus abdominalis | Beetles In The Bush