Well, that was interesting.
Thanks to those of you who gave helpful replies. I think now I will be comfortable using this stuff as directed.
A more natural treatment scheme is a goal of mine, but right now I have some mites to kill and little time to fool with it. BTW, I tried a more natural treatment previously (hopgaurd 2) and suspect, though I can't prove, that it may have been the cause of one hive going queenless this spring until I rescued it with eggs & brood from another colony. I'm way at the bottom of this learning curve, I admit. Just my second year and three hives, with no loss so far.....trying to keep it that way as much as possible.