The 20-incher stone is flat-out buggy. And in the pre-runoff spring waters of western Montana, this fly makes a great bottom-rolling skwala imitation. The 20-incher features a peacock body and gold rib reminiscent of the classic prince nymph pattern, but the addition of a hare’s ear thorax, mallard flank legs and some weighted wraps make this thing a killer. I prefer to tie my 20-inchers with a smaller cone head and some slinky rubber legs, though all versions work as well or better than the ubiquitous pat’s rubber leg, and is a damn sight better looking as well. This tutorial from In The Riffle will show you how to tie the basic pattern, which fishes best in a size 8-10 for the skwala hatch. Twist some up and drop them in the soft edges of the Bitterroot, and soon you’ll be tightening lines on big trout. One last thing- these get deep fast, and sometimes tend to stay there. Tie up a few more.