Lay a thread base from behind the eye to above the barb. Run a tiny drop of Zap-A-Gap along the rear shank.
Tie in a black goose biot by the tip at the bend, notched edge up, and wrap it forward in touching turns over the rear two-thirds of the shank to build a slim, clearly segmented abdomen; tie off at the 65% point.
Tie in one white CDC feather by the tip at the 65% point as an upright post about one shank length tall. The buoyant CDC post holds the head up so the biot abdomen hangs down vertically like a rising midge.
Tie in a grizzly rooster hackle at the base of the post, then dub a small ball of Adams gray Superfine around the thorax area.
Wind the grizzly hackle 3-4 turns parachute-style around the base of the CDC post and tie off; trim the excess.
Whip finish behind the eye and add a tiny drop of cement to the thread.