Re: oxalic vapor
A few points. I DO think that OA ca be hard on bees, queens especially. I haven't had large kills with it or anything, just my $.02, but I think OA contributed to supercedures. Vapor also requires a good deal more handling caution (albeit readily addressed) due to the inhalation risk.
But the broader point is that even with a comparatively less-harmful treatment like OA treating according to a schedule (whether they need it or not) can be greatly improved upon by using IPM. Integrated Pest Management means you monitor your mite levels and treat only colonies that need aggressive chemotherapy, and that you use least harmful methods first such as screened bottom boards and drone trapping (the only treatments I've needed for two years now).
Bees, brews and fun
in Lyons, CO