This fly is tied on a size 10 hook and imitates the freshwater shrimp. The tail and the beard hackle are brown partridge; the grey dubbed body and Firefly’s Hot Bead are covered by a clear shellback that is tightly ribbed down with nylon monofilament.  On rivers fish this pattern in a team of two flies with a more weighted fly on the point and this on a dropper 12 inches up.  Cast upstream and retrieve to keep pace with the current.  Takes will be very subtle, so watch the end of your fly line carefully.  On lakes cast as a single fly into the weedy, shallow margins.  Use all season on running water, but works best in late season on stillwaters.