Start thread and run a base to the bend of the hook.
Tie in a loose, shaggy Antron/sparkle-yarn abdomen so it forms a translucent, mop-like pupa sack at the rear that will trap bubbles and hold water; keep it loose rather than tightly wrapped.
Dub a slim thorax forward from the abdomen to the front third of the shank.
Stack a clump of natural elk hair and tie it in over the top as a down-wing/overwing, tips reaching to about the bend; secure the butts.
If desired, wind a turn or two of brown/ginger hackle at the front as a sparse collar and tie off.