Start yellow thread on a #16 curved-shank (Klinkhammer) hook and run a base back toward the bend.
Bind in about eight cream hackle fibers as a tail at least one body-length long, angled slightly downward. There are too few butts to make a step, so bury them forward rather than trimming.
Return the thread to the rear, wax it, and dub a thin noodle of yellow synthetic dubbing forward to about a third of the shank behind the eye. Keep it slim; mayfly bodies are thin.
Cut a strip of garbage (or shopping) bag about a quarter inch wide. Pull it until you see it stretch slightly, then fold it over on itself two or three times into a small bow tie with a flat pinch in the middle.
Catch the bow tie in by its flat middle where the thread sits at the front of the body, then take X wraps forward-to-back and back-to-forward. Leave the wings leaning out spent-style rather than posting them upright.
Pull the wings up and trim them roughly to length, a little above where the hackle will reach.
Tie in a slightly undersized cream dry fly hackle just behind the wings. Take two wraps behind the wings and about three in front.
Sweep everything back and take a few wraps to make a flat landing for the head, then whip finish before snipping the excess feather.
Snip or singe any fibres crossing the eye so tippet can pass through it.