Think of this fly as a stand-in for the Prince Nymph. Some might call it an attractor. Others, including some trout, I think, would take it for a specific food source. Tie it large to imitate a stonefly. Weight it heavy to use as an anchor pattern for dredging with a smaller nymph. Tie it small and it can double for mayflies and tiny stones.
Fish the Duke Nymph beneath a strike indicator. Set the distance between fly and float at twice the depth of the run. Cast upstream, throw a mend above the fly and then dead-drift it along the seam of the riffle.
Tie this pattern on a No. 6-16 scud or curved-shank nymph hook. Slide a brass bead up to the eye and wrap the thread down to the bend. For the tail, tie in two black goose biots. Wrap the body with red and copper wire. Tie in a brown saddle hackle and form a collar. Finish with two white biots for the wings.
— Gary Lewis, for The Bulletin