Zelon / Antron Amber or olive zelon antron (trailing shuck)
Fine dry-fly dubbing Olive/gray to match hatch (abdomen)
Rooster hackle Dun or grizzly rooster hackle (1 feather (Splitsville brush))
Fine dry-fly dubbing Thorax shade (thorax)
How to tie it
Start thread and tie in a sparse tuft of Zelon at the bend as a trailing shuck, about half a shank long, to imitate the nymphal skin.
Dub a slim tapered abdomen forward over the rear two-thirds of the shank.
Catch a doubled loop of thread in front of the abdomen and lock it upright with backward wraps as the hackle post.
Tie in a dun or grizzly hackle dull-side up and wrap it up and down the thread loop over a short length, then tie down the tip.
Dub a small thorax in front of the hackle brush, stopping short of the eye.
Pull the loaded hackle loop forward over the thorax and bind it behind the eye so the fibers cage flat around the top. This rides the fly flush in the film like a struggling emerger.