Because of the nice weather in winter and spring the varroa populations have exploded. Winter treatment against varroa using oxalic acid is used during winter because that it is the only time that the colony is not expected to have any brood. A single treatment should impact all varroa as there should be no varroa protected inside caped brood cells.
But because of the mild weather this winter there is a good chance that the bees did have capped brood, most likely filled with varroa. And then there was the mild spring which gave the mites a head start in the bee season letting their population grow to new heights.
That is why this year the varroa treatments here in western Europe are especially important. Varroa can be a major cause in colony death over winter. More so than lack of food or extreme cold.
The local apiarists organisation in the Netherlands has published an article on the explosive varroa population growth. A beekeeper counted 4 times the varroa he would count in an average year. You can view a translation of the article by following this next link (in all honesty the translation isn’t all that good, but kind of readable).
I’m not sure how the varroa population is going in my hives. I’ll check the mite drop after the 5 weeks of apiguard treatment tomorrow and update this post accordingly (if the weather allows, lot of rain here lately).
Talk to you soon,
I’m using a, for me, new tool in my effort to combat varroa in my colonies, apiguard. You place a “serving” of apiguard on top of the top bars of the frames and leave it there for two weeks and repeat.
From the Apiguard website :
Worker bees climb into the Apiguard tray, remove the gel as a hive-cleaning behaviour and distribute it throughout the colony. The gel sticks to the bees’ body hairs and, as the bees move through the hive, particles are left throughout the hive. The worker eventually throws out the gel it is carrying, but the traces remain until they too are removed later.
The gel acts like a slow thymol release agent. Thymol is a naturally occurring substance that has proven to work as an anti varroa agent as well as being an antimicrobial and fungicidal substance. Seeing my earlier experience with formic acid, this perhaps is a good alternative. Although I forgot to place a bottom board in the hives to see the varroa drop, thus making it hard to compare it to the formic acid treatment. But perhaps I’ll see less varroa in December when I treat with oxalic acid because of this treatment.
You do need to be done with your honey harvest because the thymol will also dissolve into the honey giving it a distinctly unpleasant taste. You should also not feed the bees while giving this treatment because the bees will be to busy with storing the feed syrup to disperse the thymol gel.
Otherwise Sif and Artemis are looking good. Next on the todo list is judging the fitness of the colonies in the light of winter survival. Will need to asses their size and food supply to estimate how much feeding they will need.