Start thread at the 65% point and lash a small pair of dumbbell eyes to the TOP of the shank (they will ride down so the fly swims hook-point-up) with tight cross-wraps; add a drop of cement.
Turn to the bend and tie a sparse clump of white bucktail on the underside as the belly, one-and-a-half shank-lengths long.
Add a few strands of pearl flash, then tie the olive/tan bucktail wing on top, slightly shorter than the flash, keeping the whole silhouette slim so it will not foul.
Advance the thread to just behind the dumbbell eyes.
Spin or stack a fox/synthetic brush around the shank in front of and behind the eyes to build a full 360-degree bulkhead collar.
Wrap the collar tight, sweep the fibers back, and figure-eight around the eyes to seat a blunt front face.
Trim the spun collar to a blunt, tapered bulkhead head, add optional stick-on eyes, whip finish and coat the thread wraps with resin or head cement.