The Peacock Stonefly nymph trout fly is one of the most useful and effective trout nymph patterns, and the 2 beads make it even better Heavily beaded for getting deep in the water column quickly Excellent trout, bass, salmon. panfish or steelhead flies. Pack of 6 - 2 bead Amber peacock Stone Fly Nymph Flies - Hook Size 10 Essential on freestone rivers where insect nymphs and larvae are an important trout food.