Start black 140-denier thread at the rear of a size 10 standard dry fly hook. You only need a base at the back for now.
Stack a thick clump of natural deer hair and tie it in at the bend as a tail, at least a body length long, using a medium wrap first so it does not flare, then cord the thread up with a clockwise spin and take a tight wrap forward to lock it in. Trim the butts.
Comb the underfur out of a medium clump of spinning deer hair, lay it across the shank at about a 30-degree angle where the thread hangs, take two loose wraps, then use the third and fourth wraps to spin it around the shank.
Pull any hair that has swung down into the hook gap back up with a bodkin, zigzag a wrap up through the clump, and move the thread just in front of it.
Pack the hair back hard with a hair packer (or a bottle cap with a hole in it), then spin and pack three or four more clumps the same way. Packing tightly keeps opening up more room on the shank than you expect.
Stop while there is still room for wings and hackle, whip finish the 140-denier thread and cut it off so you cannot nick it while trimming.
Trim the spun body with a razor blade to a tapered hex-mayfly shape (thicker at the front, tapering back to the tail) then fine-tune with scissors, being careful not to cut the tail off.
Restart 70-denier thread in front of the body, tie in a grizzly dry fly hackle with barbs about one and a half hook gaps long, right up against the front of the deer hair body, and bind the stem forward.
Tie in the two wide grizzly hen tips one at a time, spent, so they sit out at 90 degrees from the body and roughly in the plane of the hook; leave the stems long to help hold them in position, then trim.
Wrap the grizzly hackle forward through and around the wing bases in four or five turns, jostling the wings into position as you go, then tie off and trim.