Another old pattern, that I was introduced to by Harry Teel in the mid 80’s. A simple pattern that seems to not equate to any bug you have seen. I have used it with success on B.C. lakes and Oregon streams. Tie it in a size 20 Griffith’s Gnat style (midge cluster~no fore/aft hackle~palmered hackle) or a size 12 (caddis). The fore and aft hackle provide some movement and buginess and the peacock is magical. It is a fragile fly. After a dozen fish it will most likely come apart at the hackle. Just have enough on hand if traveling to have it available, should it be part of the solution to successfully solving the puzzle.