I use these as a dropper fly, hanging a couple feet below something bigger and heavier–either a beaded chironomid, a soft-hackle wet fly, or a doc spratley.
Hook: size 14 red nymph hook (Daiichi #1273)
Thread: black 8/0 (or black single-strand floss)
Gills: white marabou
Rib: silver holographic tinsel
Cheeks: silver or red tinsel
1. Tie in white marabou gills, ends forward. Leave them about an inch long for now. Wind down body over the marabou 1 or 2 mm to add a little bulk to thorax. Snip off excess.
2. Tie in tinsel rib and wind down over it to curve of hook.
3. Wind thread back to base of thorax.
4. Wind rib up to base of thorax and tie off.
5. Wind thread to top of thorax, at base of gills. Double a strand of tinsel onto your thread and tie it in underneath the thorax.
6. Wind back to base of thorax, tying down tinsel along the bottom as you go.
7. Build up thorax with thread, then move thread in front of gills.
8. Bring one of the tinsel ends around the far side of the thorax and across the hook in front of the gills, just behind the eye, and tie it down. Repeat with the other strand, on the near side of the thorax.
9. Tie off, and lacquer the whole fly with your favorite shiny glue. Be careful not to get glue on the gills (keeping them long allows you to move them out of the way as necessary). Let dry and repeat for a smooth, shiny finish.
10. When dry, snip marabou gills to preferred length (I do it at the hook eye, about 1 - 2mm or so).