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 (and a few others I collected but didn't photograph) appear to represent the first finding of Paraleptophlebia sculleni outside the Oregon Cascades, although it is not a monumental leap from there to the Washington Cascades. The key characteristics are fairly clear.
This mayfly was collected from Mystery Creek #249 in Washington on July 25th, 2019 and added to Troutnut.com by Troutnut on July 26th, 2019.