Holographic Flashabou Brown holographic flashabou (2 strands, thorax)
Spooled Antron Fluorescent white spooled antron (gills)
UV resin (coating)
How to tie it
Start rusty brown 70 denier thread and build a slight taper along the shank, leaving a little more room than usual behind the eye because the gills go in up front later.
Snip about an inch off the thin end of the tapered synthetic quill and tie it in at the rear, then wind it forward in touching turns. Because the quill is tapered, each wrap lays down a slightly larger segment, which gives you natural-looking segmentation without any ribbing. Try different underbody thread colours with the same quill; the translucent quill takes on whatever is underneath it.
Tie in bright orange stretch floss underneath and work it backwards, covering the orange with thread as you go so the wing buds come off clean at the front rather than showing as a stripe down the body.
Capture two strands of brown holographic Flashabou along the side of the shank and wrap them side by side over the thorax to cover the thread. This is just a touch of shine where a real pupa carries its gas bubble.
Pull the orange stretch floss up and over the thorax for the wing buds, trim, and cover the butts.
Tie in fluorescent white Antron for the gills with two or three wraps, spin it sideways, take a wrap behind, then cross-wrap to split them and one or two more behind to prop them forward. Whip finish behind the gills rather than in front so the resin locks everything in.
Pull the gills straight up, trim them short, then coat the whole fly with UV resin and cure it. The resin magnifies the quill and makes the segments pop.