I had the pleasure of hosting the ‘February’ meeting at my house today, March 3rd. We started by taking a look at my Warré hives. The overcast skies and temperature of around 6°C meant that only the occasional bee showed her nose at the hive entrance. So rather than looking at flying bees, we contented ourselves with studying the hives themselves, discussing some of the non-standard features. These include slightly thicker timber in the construction, and observation windows on the sides of the hive rather than at the back (or front). The latter give a view of the whole of one face of the end comb in each box rather than a view of the edge of several combs in the standard arrangement. We also looked at the small supplementary top entrances that I use in winter and the box that covers the main entrance, which incorporates a mouse-proof slot. The hives also have sump floors, one of whose functions is to make it easier to fix legs to the hive that sit well outside the hive footprint, increasing hive stability. Another is to allow a place for hive debris to sit, encouraging a diverse in-hive biota.
And also take a very brief peak through one of the observation windows to see the bee cluster in a corner, before gently replacing the window cover. It seems that the bees do not consider the window to be cold, so presumably the cover is keeping things snug:
We then moved inside to tea and cake and a talk about the natural defence mechanisms that the bee has against varroa. The talk was based around some modeling that I did a couple of years ago, using varroa data from my own hives and published models of in-hive varroa population dynamics. The talk combined this with a summary of the published research on the many ways (physical, physiological and behavioural) that bee colonies can potentially restrict varroa numbers. The conclusion was that the degree of natural inhibition needed to limit varroa numbers to acceptable levels is not large. This is because the control mechanisms that the bees use are continuous, whereas interference by the beekeeper is, by its nature, one-off. A small level of continuous control turns out to be far more effective than even large levels of one-off control. For example, chemical treatment (such as essential oils) needs to be over 85% effective to have a significant impact on varroa numbers. Daily interference by the bees needs only to be 2% effective to give the same result. The mechanisms that are potentially available to the bees each need to contribute only a part of that 2%. I explained my strategy of concentrating on the creation of in-hive conditions that allow my bees to deploy those defences and then standing back and trusting my bees to get on with it.