This fly is one of the most popular nymph patterns and a very important one to have in your box. It is an impressionistic fly to represent a wide variety of aquatic nymphs such as mayflies, stoneflies, and caddis. I always carry at least 6 each in various sizes from 12 to 18. It is irresistible to many fish such as trout and pan fish. When you don't know what to fish tie one of this on as a top nymph or a bottom nymph.