This is a picture of Kimberley suited up to put formic acid in the hives to treat for varroa mites. Formic acid stinks, and the vapor burns. Makes your nose feel like it’s been toasted, your eyes feel like they’ve been torched. Our advice: Wear a respirator. Wear eye protection.
We’ve treated with formic acid once, although just on Veronica. It didn’t seem to help; a week afterward, we sugar dusted, and the sticky board from Veronica was still covered in mites. Lot’s of the little vampires—almost 200 in five minutes! Even natural 24-falls yielded high counts.
To kill mites, formic acid needs daytime outside air temperatures to be between 50-79 degrees. The first time we applied formic acid we had a cold spell, and the temperature never reached optimum levels. Perhaps that’s why we didn’t kill so many mites. For this second application we’ve been in luck, with summer-like weather during the first two weeks of January. We put the formic acid in Veronica on January 14, and we’ve been slaughtering mites ever since. Hundreds, maybe thousands. Too many to count.
Betty gets a formic acid pad for only a few hours during the day. She’s too weak to live with the vapor for longer periods of time. She doesn’t have as many dead mites, but still there are enough to be worrisome.
Formic acid may slow down spring brood production, but the mites will weaken and eventually kill the hive. We’ll take the pad out of Veronica the first week of February. We hope this works.