Tie in a sparse bunch of wood duck flank as a short tail.
Catch in copper wire at the tail base.
Dub a rough body of tan Australian possum forward to the 70% mark, then rib forward with the copper wire in 5-6 open turns and tie off.
Tie in a small bunch of wood duck flank and distribute the fibers all the way around the shank as a collar. This breathing collar is the whole point of the fly.
Dub a fuller thorax of the same possum in front of the collar.
Build a small head, whip finish, and cement.
Substitutions
Body instead of Australian possum dubbing: Hare's ear dubbing — Same buggy texture; Muskrat with guard hairs — Natural, slightly finer
Hackle instead of Mallard flank: Wood duck flank — Barred, classic; Partridge — More mottling, softer
Other versions
3 more in the app: Copper Bead, Bead Head, Beadhead.