Start the Brown UTC thread and dress the hook, keeping the wraps sparse to hold down bulk, running just past the barb.
Bind one Hairline Mayfly Tails fiber to each side of the shank at the rear, then advance the thread up the shank.
Tie in the brown stretch tubing for the body at the front and bind it back.
Split the tails into a V by passing the thread between them and tying it off.
Take the thread to the eye, then wrap the tubing forward in touching wraps for segmentation. Tie it off at the eye.
Whip finish the brown thread with a simple one- or two-turn finish - keep it small - and cut away.
Start the Yellow UTC thread at the head and lay the White Bett's Standard Z-Lon over the fly. Take one wrap toward the eye, fold the Z-Lon back, and wrap over the fold to make a crease so the wing lies back toward the bend.
Whip finish, then cut the wing to the length of the body - nothing past it. Add UV resin to the head where the wing is for durability.