The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
This family contains a single genus, Pentagenia, with two species. They are large mayflies with burrowing nymphs, similar to brown and eastern green drakes (Ephemera) and Hexagenia, but they are not found on trout streams in adequate numbers to be important to anglers.
Where & when
In 70 records from GBIF, adults of this family have mostly been collected during June (39%), July (21%), August (20%), September (10%), and May (6%).
In 10 records from GBIF, this family has been collected at elevations ranging from 823 to 6247 ft, with an average (median) of 3576 ft.