This may have a proper name, I don’t know what it is though.
Hook: #20 Tiemco 2487BL scud hook
Bead: Micro 5/64” #18/20 (ran out midway through and switched colors)
Thread: Gudebrod 6/0
Rib: Danville’s fine wire, gold
Slip on bead, clamp into vice
Tie in right behind bead, three wraps up front to help hold bead in place, drop of head cement.
Wrap back deep to mid-shank, tie in light wire
Wind over light wire to deep into hook bend
Wrap thread tightly forward to bead, build up fat cone at front
Wrap rib forward, tie down with three wraps right behind bead to finish cone
Three whip finishes, heavy cement. I put a fat drop, let it soak, then sweep the leftover right down the back of the fly.
I have also used the smallest size of chenille to put in a thorax. It’s one more step, doesn’t hold up quite as good, but makes a buggier look. Might look more like a set of gills than just the fat thread up front. I think it slows the sink a little bit though.
Could omit the bead for slower sink, or use tungsten for faster sink, I like the bead because it makes it sink so well, and adds flash – I like to use this as a dropper behind a bugger in lakes, it seems to get hits when I fish it slowly.
Could also tie in at mid-shank or at bend and spin the thread so it’s flat for a real slender body, might be a more accurate imitation, but I like a fat little body because I think the fish think they’ve found a particularly juicy chiro when they see my plump little offering.