It is often asked why a colony dies during winter in temperate regions even though plenty of stores are found in the brood combs and supers. This is especially frustrating to those who carefully obey the maxim to leave the bees enough stores for winter. The size of the cluster of bees that cluster (bunch together) to survive cold weather is all important in wintering. If the cluster is too small, the population is not efficient in producing and conserving heat. In terms used by physics professors, the cluster’s surface to volume ratio is inadequate.
The fall bee population is made up of winter bees, which are programmed to save energy. Any reduction in brood rearing in autumn translates into fewer winter bees going through winter. A certain number of these specialists are needed to produce and conserve heat in the cluster and begin the arduous work of population buildup the following Spring.
A late honey flow can be a major reason for a small cluster. In their frenzy to get the last drop of a bumper fall nectar crop, the bees may pack the brood nest with honey and the queen’s egg laying space can become restricted. She becomes “honey bound” with no room to produce the necessary brood that would develop into winter bees to provide a cluster with an adequate surface to volume ratio.
Any fall reduction in egg laying can translate into a smaller cluster size. Thus, if a queen’ egg laying becomes restricted for any reason, empty combs must be provided in the brood chamber or an inadequate winter population may result. Bees have the ability to regulate their own population. They can increase/reduce the food given to the queen, resulting in more/fewer eggs being laid. Young larvae may even be consumed on occasion, a more drastic population control method.
Wintering honey bees in cold temperatures takes into consideration many variables. Canadians and those in the Midwest have many years of experience. The relationship between temperature and moisture is important.
Here’s an excerpt of a discussion on how Rudi Peters handles these issues in British Columbia:
- condensation = when water vapour becomes liquid water
- moisture = liquid water, either diffused in a solid or condensed on a surface
- humidity = the % value of water vapour in the air
“Rudi emphasized that it is condensation dripping down onto bees from a cold inner cover that is the winter colony killer. Humidity and moisture do not kill bees, but condensation can.” See more at the Herewebee website.
In subtropical and tropical conditions, winter (i.e. cold weather) is not much of an issue and so the surface to volume ratio of the cluster is not necessarily a key to survival. More important is moisture availability.
During optimum times, overpopulation may cause a colony to send off half its workers with a queen to another nest site. This behavior known as “swarming” is the way honey bees increase their population, but it inevitably reduces the beekeeper’s ability to control the number of honey bees in a colony. For the honey producer, swarming is often nothing more than nuisance and its presence will dictate whether the beekeeper gets much of the sweet reward for his/her labor.