That would be a
Pheasant Tail Mahogany Dun Emerger with 90 Degree Hackling.

There have been lots of cutthroat trout taking emergers on my home water recently, but there is no way to get into the part of the crick where they have been feeding to sample what is in the drift. Since there is reportedly a hatch of mahogany duns on this river this time of year, I decided to treat the trout to a new version of one of their staples.