When I lived in Utah, I used to hang out at "The Fly Line" a fly shop in Ogden, Utah. The owners were Bruce and Mims Barker. While there, I was introduced to this fly by Mims. He developed this pattern while fishing for months on the Henry's Fork below Island Park Reservoir. They had a family residence on the banks of the Reservoir.
This pattern was written up in Terry Helleckson's Book: "Popular Trout Patterns". It consists primarily of wool yarn.
The tails are dark brown biots. The abdomen is tightly twisted black yarn. The wing case is pheasant tail pulled over. The hackle is a furnace. The thorax has lead-free wire for weighting.
Anyway, I will be in Box Canyon in early June and thought I would tie some up.