I've been tying some "pretty flies" lately for the green drake hatch on Penns Creek in central PA. For the extended bodies, I've been using the pattern described in Stalcup's book. What to use for dubbing. Hmmm. I'm doing a drake spinner, so the body needed to be translucent white. Well, I've finally found the perfect material, silk. I had some tussa silk from my wife's wool spinning. You can buy it via Ebay.
I tried a lot of other things, but it turned amber once the flexament got into it. Tussa silk stays pure white with the transluceny that one would want. Absolutely beautiful. I'll post some pictures tonight.