Crystal Flash Pearl, coloured black (1 strand looped, horns)
Liquid Lace, mid size Light olive green liquid lace mid size (underbody and rib)
Chironomid skin, clear Clear head cement (body)
Permanent marker Black ostrich herl (horns)
How to tie it
Start light olive UTC 70 up front on a size 12 scud hook, ahead of the 3/32 black bead position. Tie a piece of pearl Crystal Flash in on the near side and loop it over to the far side to keep bulk down, then sweep both ends back and take two or three wraps to stand them up. These are the two devil horns a chaoborus pupa carries.
Shorten the horns, then colour them with a black Sharpie, just touching the black on so a hint of pearl still shines through. The naturals are almost a see-through black, and that is exactly what you are after.
Slide the bead back up, re-attach behind it and start a light taper as you would on any pupa.
Tie the light olive Liquid Lace in against the near side with a couple of tight wraps and then really pull on it as you bind it down into the bend. Keep the tension on and do not let go, because the moment you release it the lace swells back up and you end up with a chunky butt.
Still holding that tension, capture the clear chironomid skin and wrap it forward in tight side-by-side turns over the whole body. That clear layer is what gives the gassy, translucent look; a thread-only version photographed alongside it is not close.
Wrap the Liquid Lace forward under good tension as the rib, leaving small gaps between turns. It is a slippery material over a slippery material, so lock it off with plenty of thread tension and a couple of wraps over and behind.
Whip finish, then bend the horns up over the bead so they stand and trim them to length.