This is really a Willy Self fly. I haven't seen Willy tie it exactly this way. But Willy ties a lot of flies. Tying midges with hot fluorescent bodies and ice dub wings I learned about from Willy. These flies work all year long. But they do seem to be particularly hot for winter fishing. This one is tied on a #10 scud hook. Bigger than the ones I use on the rivers.
But we're going to hit the reservoir tomorrow (Turkey Day). And that's a whole different story. If you shine a UV flashlight on these things they light up like a Christmas tree bulb. And UV light does penetrate deeper than anything in the humanly visible range. So it seems likely these flies do glow a little, even at depth. They sure do catch a lot of fish. Edge Bright body. Black wire ribbing. Bead and Pearl Ice Dub wing. Thin CA glue (ZapCA) to hold it all together.
Green Rock Worm variant: