13/12/2025
Mid-December hive inspections were not on my 2025 bingo card… but the rules are sometimes different with the research hives. It was fun to get a winter bee fix in yesterday when checking to see which colonies still have brood, and I thought this was a great visual representation of the “winter cluster” to share with you.
The third and fourth photos are shots of the bottom and top boxes, respectively, of a single colony; see how the bees are gathered together towards the middle frames? This is the cluster, and the population will contract into an even tighter, smaller area as temperatures drop. If you think of the cluster as a basketball (in this case, spread between the two boxes and roughly in the middle frames), the outer layer of bees provides an insulating shell, while bees on the interior vibrate their wing muscles to generate heat. The bees rotate through so nobody has to be on the outside for too long, and if they’re raising brood, they will keep the core temperature around 93F no matter what the temperature outside is - cozy!
In a two-deep setup, the bees will typically start winter in the bottom box, moving their way up as they eat through their winter honey stores; the cluster pictured here is still spread between both boxes. By spring, we’d expect most, if not all, of these bees to be in the top box.
Winter clusters are so cool - one of the incredible things bees do that allow colonies to survive the winter without hibernating.