Dr. Marion Ellis from the University of Nebraska spoke at an NCSBA bee conference in 2016 and covered a couple of methods for using oxalic acid to eliminate varroa in the hive. The trickle or drizzle or dribble method is one of the ways to treat. According to Dr. Ellis, this method is applicable only in winter when the bees are broodless and clustered with temperatures between 32 and 41 degrees F. A mixture of oxalic acid and sugar solution can be dribbled over the cluster, causing direct damage to any Varroa mites infesting the bees. This treatment causes small damage to the honey bees themselves, but when I did this for the first time last winter, I was convinced I was going to kill all of my colonies.
Today the temps were about 38-39 degrees so I decided this was the time to treat. I could also add more fondant where the hives had room for it and I wanted to give the bees a Christmas present of a pollen patty to help the colony along when the queen starts to lay again in a few weeks.
It was cold and sunny and I expected that the bees would be down and clustered. In colonies where the bees were down, they came up as soon as I started to drizzle. Others were up already when I took the lid off or came up as soon as the hive was open. So I don’t think I got them all, but hopefully I’ve made a big enough dent in the mite population that the spring bees will be as vibrant as the ones last year.
All five hives were doing well and I came away a very happy beekeeper.
The following video shows you how I did the drizzle. I followed the directions on the Brushy Mountain instruction label that comes when you order oxalic acid from them.