Spence,
#16 Pheasant Tail with a woven Mylar wing case
No, not the Mylar tubing that is used for streamer bodies. Gudebrod used to make this woven Mylar. But since Gudebrod went out of business a few years ago I don't know where to tell you to get it. It came in two widths; one about 1/8" and the other about 3/16". I used the narrower for smaller nymphs #14 - #18 and the wider for #10 - #12 nymphs. I've posted pictures up here before showing that wing case. I'll look to see if I can find a picture.
I Googled "Mylar braid" it took awhile but I found this link. It is called "Flat Diamond Braid". I use the pearl for many of my nymph wing cases but you can use whatever color you want.
http://www.fishusa.com/product/Flat-Diamond-Braid?
The other fly that was really very productive was a special tie of the emerald shiner. We were just casting it slightly up and across with one "B" split shot and let it settle down in the pools or pods of fish if we could see them. Often they would just hammer it as it drifted through the dark water. Very violent strikes. It is a complicated recipe and might be hard for me to put into words. When I have some more time I'll try to explain how it is tied.
Here is a picture of many of my nymphs tied with the woven Mylar wing case. The pheasant tail nymph I used had a wood duck fiber tail, twisted pheasant fibers (4-5) wrapped around the shank and counter ribbed with extra fine gold wire. The thorax is a dense strand of peacock herl through which I wind a webby brown hackle, then pull the woven Mylar over the thorax and tie it off. A variant of this fly is adding a 3/32" or 1/8" gold bead. If you want to get creative try adding a "hot spot" in front of, or behind, the peacock herl.
As I look closely at the picture I see the entire top row of flies are "flashback PT's" but these are all much bigger, probably #10 - #14.