A size 10 fly that imitates the Mayfly nymph. This pattern is tied on a curved hook to suggest the swimming motion of the nymph. The body is cream Nymph Skin wound over ostrich herl, which pokes out at the bend of the hook to suggest the tails and the front of the hook to suggest the legs.  The fly is finished with a wound hackle of olive CDC feather.  This pattern will fish in the surface film, due to the C.D.C. feather, and trout will take it as the emerging Mayfly. This pattern will work on running water and stillwaters, and its most productive time is from the middle of May to the middle of June.