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.
In 1217 records from GBIF, adults of this family have mostly been collected during June (24%), July (21%), May (18%), August (17%), September (7%), and April (6%).
In 610 records from GBIF, this family has been collected at elevations ranging from 10 to 23622 ft, with an average (median) of 3652 ft.
To further identify a specimen of Rhyacophilidae to the genus level, use the Key to Genera of Rhyacophilidae Adults.