Anyone out there heard of this fly? It was supposedly a standard in the Yellowstone area 30 to 50 years ago, but I can't seem to find a reference to it anywhere. I'm doing a little research for my friend Bruce Staples and I'd like to get a lead on this bug. It was a pattern that was tied in dark gray or lighter tan and represented a large stonefly nymph. And no, it's not related to the Mepps spiiner lure of the same name.

Any help would be appreciated.