I developed this Mr. Rapidan to match the emerging form of the Quill Gordon naturals and its the most effective fly I have found for this. Fish it upstream with a slow rod lifting motion from the riffles all the way down into the main part of the pool. I also do well with this on the large streams in Montana by fishing across stream below the riffles with a slow swimming action. The size 10 in this is a great fly for smallmouth bass on the Shenandoah River when the hexagenia start hatching in September.