Those of you that use one last OAV shot when the colony is broodless in the fall winter, how late in the year do you do this? Also, is it still accurate that it is okay to use OAV when sugar blocks are in place?
You can do OA pretty much anytime, but you want to do it when the temperature hovers around 40-45 degrees and sunny. It is warm enough for the bees to break cluster, but cold enough for them to wonder out. Keep in mind the purpose of the OA is too kill the mites, so you need to do some calculations. In my area, Northwest NJ, winter bees are laid around mid to late september. The winter bees emerge around mid October. The best time for me to do OA is now because all the bees are hatched, the cells are empty and the varroa are feeding off the bees. If I have no time to do it now, I will try my best to do it by Vet's day.
Not sure about your winter weather/temps. but it's colder here in VT and I hold off my "one shot" until around xmas (helps you to remember when near a holiday too) when I know they are broodless. A few days ago, one of my hives had an orientation flight, so that queen could certainly still be laying. I just finished my OA series "clean up" last week because one hive had a higher count than I like. I got continued drops for 3 weeks, so I know brood was still hatching in that hive too. Unless you think the count is too high now, I would hold off on the "one shot" a little longer. J
Ya, I was in a hive two weeks ago that needed some feed and pulled a couple frames for the tank feeder. It had a grapefruit sized cluster of sealed brood and larvae surrounding it, they’re not broodless yet, I’d say between thanksgiving and Christmas
I watch the weather / temperature around Winter Solstice. I will OAV treat, twice 14 days apart, when there is going to be a sunny day and temps going above 38F, ideally above 40F. My hives are 2-inch insulated with no top exit - vent but with bottom screens and sticky boards. I am in RI coastal area.