The vaporization of oxalic acid in beehives is a proven method of killing both Varroa & Tracheal mites. This vaporizer comes with “side” wings that serve to keep the vaporizer from overturning in the hive. Load the cup of the vaporizer with one gram (per brood chamber) of oxalic acid (wood bleach) insert it in the hive and connect it to any 12 volt car battery. The vaporization will complete in 2 1/2 minutes. Disconnect the vaporizer and leave it in the hive for a minute more to seal in the vapors and you're finished! Remove it from the hive, DUNK in a pail of water (no need to use a wet rag or sponge (but you can)) & you're ready for your next hive! If any residue remains in the cup after treatment, scrape it out with a stick or other blunt object. Remember to seal the hive for 10 minutes after you remove the vaporizer to lock in the vapors. Cut pieces of foam work just great.
Oxalic acid vapors only kill the mites that are on the bees (phoretic,) not in the brood. With the hive almost broodless in late fall or early winter, that is an excellent time to treat. If the outside temperature is 40 degrees (f) or above, you can safely vaporize. You want to go into winter with mite-free hives, as the main reasons for winter losses are starvation and mites!
To treat in the summer, you must complete three (3) successive weekly treatments to vaporize the mites that are emerging in the brood. If you’ve supers on, you must also remove or place a barrier between your supers and brood nest.