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 specimen keys to the Neoleptophlebia memorialis group, which means it could be Neoleptophlebia memorialis or Neoleptophlebia temporalis. In the absence of a clear species key, I'm just guessing memorialis for now.
This mayfly was collected from the Dosewallips River in Washington on July 6th, 2020 and added to Troutnut.com by Troutnut on July 12th, 2020.