Bead Red brass (or glass/tungsten) bead (1, small)
Tail Natural India hen back fibers (few short fibers)
Abdomen White thread ribbed with black Superhair (1 strand rib)
Wing case / flashback Medium pearl mylar + white Fluorofibre (1 strip each)
Legs White fluorofibre (few fibers)
How to tie it
Slide the red brass bead to the eye, positioning it as the thorax; start white thread behind it.
Tie in a short sparse tail of hen back fibers at the bend, about a half shank long.
Bind in a strand of black Superhair at the bend to rib, then build a slim smooth abdomen with the white thread forward to the bead.
Rib the abdomen with 5-6 evenly spaced turns of black Superhair to segment it and tie off, keeping the profile thin, a baetis nymph is a sliver.
Switch to black thread behind the bead; tie in a strip of pearl mylar and a length of white Fluorofibre pointing back over the abdomen for the wing case and flashback.
Build a small black thorax collar behind the bead, then pull the pearl mylar over the top as a wing case and bind it down.
Split a few Fluorofibre fibers to the sides as legs, whip finish, snip, then glaze the back and thorax with a thin coat of UV resin.