Lew,
I tie up firefly patterns with the uni-glu yarn as an abdomen. I have great success with them, mainly on panfish, but once in while a bass will take them as well. I've been tying with the uni glo yarn for several years now, one of our local fly shops was going out of buisness and sold the spools out for $.50 each so I bought four spools to try and have been "hooked" on in ever since.