You may remember those nasty Varroa mites that live on the bees and in the brood, weakening them and making them susceptible to disease and colony decline. I treated the bees with strips impregnated with medication in the Autumn but that doesn’t kill the mites living in the capped brood cells. When the brood emerge, so too do the new Varroa mites, and the cycle starts again. So, today with the hive having either no or very little brood it was time to treat the bees with Oxalic acid.
This is a highly effective treatment against Varroa with a 90% efficiency. However, it will not penetrate the brood capping, hence doing it at the most broodless time. Vaporised Oxalic acid is not toxic to bees but is highly toxic to Varroa mites and to beekeepers!
Having seen a demonstration of how to vaporise Oxalic acid at one the East Lothian Beekeepers Association meetings, my friend Fraser and I borrowed their equipment and arranged to meet up today to treat my hive, and then to treat his hives.
Firstly, Fraser and I read the instructions carefully! I blocked the entrance so no bees could escape. I then inserted a solid board below the open mesh to create a floor. I removed the fondant from the top and plugged the hole with some foam. We put on our protective equipment and I inserted the crucible on the new floor, plugged the gap with moist foam, linked the crucible to the battery and vaporised the acid. This was done for 2.5 minutes, disconnected from the battery and the crucible left in the hive for a further 2 minutes and then finally, the crucible was removed and dipped in a bucket of cold water to cool, with the hive remaining closed for a further 10 minutes to allow the vapour to act on the Varroa mites. When time was up, I removed the foam and the solid board floor, reinserted the Varroa count sheet and reopened the entrance.
I will return in a week and count the Varroa drop on the count sheet. I’m hoping any Varroa not killed in Autumn will now be dead and the bees can look forward to a healthy start to the spring.
We then headed off to Fraser’s apiary and repeated the procedure. I’m glad to say no bees or beekeepers were harmed in the vaporising!
A big thank you goes to Stuart for pulling the trolley with the equipment and a very heavy battery, to Fraser for suggesting we treat the bees this weekend and for his help with the process and to the East Lothian Beekeepers Association for their advice and loan of the equipment.