Double Bead Stone Fly Nymphs. Versions: 20 Incher, Golden, Natural, Olive, Peacock (Amber or Black biot legs), Double Bead Stonefly Nymphs are a variant to the standard bead head version Mostly used during the Salmon/Stonefly hatch but can be effective all year long. The Double Bead version gets your fly down quick! Sizes: # 04 - # 18