Start the olive thread behind the eye and lay a smooth thread base back to a point directly above the barb.
At the bend tie in a small pinch of olive Z-Lon as an under-shuck about one-third of a shank length long, then lay 4-6 natural mallard flank fibers over it the same length so the tail sits slightly splayed. The trailing shuck imitates the nymphal skin the emerging dun is still stuck in.
Tie in one BWO-dyed turkey biot by its tip at the tail with the notched edge facing up; wrap it forward in touching turns to the 65% point to build a slim, clearly segmented, tapered abdomen and tie off.
Stack two dark dun CDC feathers tip-to-tip and tie them in standing upright at the 65% point as one bunched wing about one shank-height tall; trim the butts.
Dub a sparse noodle of BWO Superfine and build a small thorax behind and in front of the wing, then draw the CDC tips forward over the eye ('captive' style) and lock with 2 thread wraps so the wing angles forward over the thorax.
Whip finish under the wing and add a tiny drop of head cement to the thread only, keeping the CDC dry.