Thread To match body (olive, primrose or grey) 8/0
Materials
Tail Stiff cock hackle fibers to match (6-8)
Body Fur dubbing or herl in the dun's color (small amount)
Thorax Same dubbing, doubled (small amount)
Hackle Quality cock hackle to match the natural (1 feather)
How to tie it
Start thread behind the eye and wrap to the bend. Tie in six to eight stiff fibers as a tail, slightly spread to aid balance.
Dub or wrap a slim abdomen to the 65% mark.
Build a slightly pronounced thorax from the 65% to the 80% mark, the thorax bulge suggests the wing roots and legs, which is what lets a wingless fly pass for a dun.
Tie in one high-quality cock hackle at the 80% mark.
Wind 4-5 close turns of hackle, tie off, and whip finish. The hackle fibers do triple duty as legs, wings and outrigger floatation.
Optionally trim a shallow V in the fibers underneath so the fly sits lower and cocks upright every cast.