Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
This wild-looking little thing completely puzzled me. At first I was thinking beetle or month larva, until I got a look at the pictures on the computer screen. I made a couple of incorrect guesses before entomologist Greg Courtney pointed me in the right direction with Psychodidae. He suggested a possible genus of Thornburghiella, but could not rule out some other members of the tribe Pericomini.
The only species of this genus, Diphetor hageni, is one of the most important in the Baetidae family for western anglers. It was previously known as Baetis parvus in the West and its synonymy Baetis devinctus in the East.
Where & when
In 14 records from GBIF, adults of this genus have been collected during June (29%), April (29%), July (14%), August (14%), December (7%), and May (7%).
In 8 records from GBIF, this genus has been collected at elevations ranging from 700 to 8871 ft, with an average (median) of 5420 ft.