I live in the Pacific NW and Hop Guard is being produced in Yakima, Washington. The Chapter 18 has gone through for WA, OR and ID only. I would say it hasn't been proven that it works. It is being pushed by a couple of commercial beekeepers who have some monetary interests in getting it approved and sold. They are pushing it on all beekeepers telling us it is the answer to your Varroa problem, but it has yet to be proven. For myself, I would rather try the Mite-Away Quick Strips. They say it will be available also in the spring after it receives it's Section 3 clearance making it available not just to WA, OR and ID, but to the whole USA. Mite-Away Quick Strips (MAQS) control both Varroa and Tracheal Mites and they also can be used during the honey flow when supers are on. If you ask me, Hop Guard, might be good, but it has yet to be proven and I don't want to subject my bees to something that hasn't been proven. Also, there is a chance Varroa will develop resistance to Hop Guard just as it did to Apistan. If you want to try Hop Guard, it's your call, but personally I would wait until it proves itself. For me, the Mite-Away Quick Strips are the ones I'm going to use.