The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
In 81 records from GBIF, adults of this family have mostly been collected during August (36%), July (31%), September (16%), June (10%), and October (6%).
In 38 records from GBIF, this family has been collected at elevations ranging from 618 to 6250 ft, with an average (median) of 3691 ft.
To determine whether a specimen of Ephemeroptera belongs to Polymitarcyidae, use the Key to Families of Mayfly Nymphs or Key to Families of Mayfly Duns and Spinners.