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.
Although I couldn't key out this female spinner, I'm fairly comfortable calling her Stenonema modestum based on the markings on the abdomen and their similarity to those on the males of this species. This one probably came from the Namekagon River, although there's a possibility it came from the West Fork of the Chippewa River, because it was found in the truck after fishing those streams on back-to-back days.
This mayfly was collected from the Namekagon River in Wisconsin on June 22nd, 2021 and added to Troutnut.com by Troutnut on June 24th, 2021.