This last fall I learned how to put a sticky board under my screen bottom board. So I did just for experimenting. The next week I pulled it out and had 300 mites on it. GASP! So I did some very thorough quick research and decided on NOD Formic acid sticky strips. It's natural and won't hang out in your wax and honey, and it kills the mites that are attached to the drones in the cells.
It was miraculous! in 7 days I had over a 2000 mite kill, and very little colateral damage with larvae and bees.
But I now have an oxalic vaporizer which I will use twice a year if need be. We just did a treatment a week ago, will wait two more weeks to see how many mites have dropped. I'll post that event then.
I'll tell ya this.... after the formic acid treatment, my bees were so much more active and happy, more came out for foraging and flights.