This pattern is tied on a size 10 hook and is an impressionistic Mayfly Dun pattern. The hair wing detached body and the heavily hackled thorax combine to make this fly very difficult to sink even in quite fast currents and choppy water. Fish it dead drift, but with an occasional twitch of the fly imitating the dun trying to break out of the surface film. Presented to rising fish, or cast in likely looked lies can result in explosive takes to this pattern. Like all Mayfly patterns this is best fished between the middle of May to the middle of June.