I bought a few packages and tyed a few flies but I hve not fished them yet so I can't answer your initial question. Saying that I shined my UV light on them and I was able to determine that what makes the material UV reflective is strands of red, blue and a few other colors in the mix. So IMO you could conceivably make your own by taking a favorite dubbing material and add some strands of florescent threads and accomplish the same thing.
There are basically two types of UV, absorption and reflective and they are going for the reflective.