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.
looks like Ephoron sp (Polymitarcyidae) to me.
Interestingly (to me at least), this is the genus of (winged lifestages) mayflies which has either (2) tails or (3) tails, depending on whether male or female.
Roger -
Do all Polymitarcyidae have 2 or 3 tails? Also which sex has 2 tails and which sex has 3 tails?
Just curious,
Mark