Considering that even non-beekeepers are somewhat aware of this particular beekeeping problem, the absence of any discussion in our blog has been rather conspicuous. Given its relevance to our last winter’s losses it is about time we wrote a few words about Varroa and our hives.
While beekeepers have always had to cope with pests and diseases in their hives the arrival of the Varroa mite was an unwanted watershed in bee management. In halcyon days of old, we are told, one could keep a more casual eye out for signs of trouble, confidently treat with medication or with manipulation, and otherwise leave the bees to themselves except when stealing their honey. Then came the Varroa and it remains a constant pre-occupation of beekeepers.
Beekeeper Emily Heath gives a comprehensive account of the pest and treatments for those who wish a more thorough coverage than our minimal summary:
- The immediate harm of the pest is that it feeds by sucking the bee’s hemolyph, the fluid that serves it as blood, and so weakens it.
- The worse harm is the various infections can now enter through the holes in the bee’s exoskeleton, many of which are carried by the mite itself.
- And finally Varroa reproduces in brood cells, stunting and deforming the developing honeybee, and growing several new mites for each infested brood cell.
That last is what makes infestation so devastating. The mite out-reproduces the bees and can rapidly bring about the death of a colony. In ecological terms killing their hosts arguably makes them an unsuccessful parasite but that is little consolation for losing one’s bees to them.
In previous years we had been ignoring the mite, trusting the lore that a first-year colony rarely has a Varroa problem since it rarely rears enough brood to allow a large mite population to grow. Planning for a second year we dithered between remaining treatment-free and making splits of the survivors or monitoring and treating with something not too noxious. While the former plan may work for some it does require at least one colony to survive the winter, a result we have not been very good at achieving. And Dr. Milbrath did point to a significant number of varroa corpses when she inspected our dead hives. And our hives have grown populous indeed.
So this year, we have been monitoring with sugar rolls, and treating with ‘soft’ chemicals when the mite count is over threshold. All three hives got thymol(Apilife Var) in July. Clarissa and Dorcas got formic acid(MiteAway Quick Strips) in October while no mites at all were found in Beatrix!
We also tried a drone frame in each hive but they were never drawn out and so we have removed those. Bees are reluctant to use plastic foundation at the best of times and it was probably too late in the year for our girls to be very interested in wax building. We will try again earlier next year, with the same bees we hope.