This nymph pattern, developed by John Barr, has been a staple for most fly fishermen for years, especially here in the Rocky Mountains. It can represent almost any mayfly nymph and the larger sizes (especially in black) work well as a smaller stonefly pattern. The wire body and beadhead allow this fly to get down into the fish's feeding zone quickly and the resin covered thorax makes it almost indestructible. Red and Black available in sizes 12 thru 22; Copper in sizes 12 thru 20.
TIP: The Copper John works especially well as the nymph in a dry-dropper set up. Try different sizes and colors 30" below your dry fly.