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 one doesn't have the protruding mouthparts typical of Cinygmula, but I think it's just an oddball individual.
This mayfly was collected from Swauk Creek in Washington on June 13th, 2022 and added to Troutnut.com by Troutnut on June 14th, 2022.