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.
A few of these nymphs turned up in my kick net sample, with this being the only one fully mature and ready to emerge. It keys pretty straightforwardly to Ameletus suffusus, particularly because of the triangular dark patch on the labrum. The abdominal markings are close but don't quite match other drawings, likely just individual variation.
This mayfly was collected from the Cedar River in Washington on July 2nd, 2021 and added to Troutnut.com by Troutnut on July 4th, 2021.