Thread Pale yellow / cream Danville 6/0 waxed Flymaster
Materials
Trailing shuck Hareline Antron yarn, dark brown (half a strand off the spool)
Wing EP Trigger Point Fibers, caddis grey (a bunch about an eighth of an inch wide when pulled taut)
Body Hareline Micro Fine Dry Fly Dub, sulphur yellow (the tiniest wisps, dubbed tight)
How to tie it
Mount a Fulling Mill 5050 Ultimate Dry and start pale yellow 6/0 thread on the shank. The thread colour is chosen simply to match the overall tone of the sulphur being imitated.
Pull a length of dark brown Antron yarn off the spool and split it in half, straight off the spool it is thicker than you want for a shuck, and on smaller flies you would thin it further still.
Catch the yarn on top of the shank and tie it in rearwards, then bring the thread back up and trim the front portion away.
Trim the shuck to length the easy way: pull the yarn up and over the hook eye and cut it off level with the eye. That gives you a shuck the length of the body every single time.
Pull a workable slip of EP Trigger Point fibres from the hank. Sean uses light dun shades on all his mayflies. He is not a believer in matching wing colour. He wants a wing he can actually see on the water.
Leave the thread hanging about two eye-lengths back from the eye, lay the wing material forward over the shank and take a couple of loose capturing wraps, then three really tight wraps to fix it.
Take a few wraps in front of the wing towards the eye and build a small thread dam there to start standing the wing up.
Trim the rearward-facing butts out. Twist the material first, then work the scissors in close to the thread base for a tight cut.
Smooth everything down and work up a slight taper behind the wing.
Dub the tiniest wisps of sulphur yellow Micro Fine dry fly dub onto the thread and spin it into as tight a noodle as you can, a tight noodle soaks up far less water.
Start the body right where the shuck leaves the hook and take even touching wraps forward to the back of the wing.
Add the remainder of the dubbing, again sparse and tight, bring it up behind the eye and then work rearwards, packing wraps hard against the front of the wing to prop it upright.
Whip finish with three or four turns and cut the thread close. Head cement can go on later if you want it. Check underneath and trim off any stray fibres.
Trim the wing last: fold it back over the body, note where the body ends, then add three or four millimetres to that and cut the wing there. Finger the fibres into shape.