Bees in Winter

The impact of harsh winter weather on bee colonies is significant. 

Colder temperatures means more stores consumed, smaller clusters and a cluster finds it harder to move across frames within the brood box.

When first formed the cluster covers most of the frames

When first formed the cluster covers most of the frames

As temperatures drop below 10C (50F) the colony uses increasing amounts of winter stores to generate increasing levels of energy and maintain core colony temperature. The consumption of stores then releases carbon dioxide and water. And without adequate ventilation, some of this water condenses on cold surfaces creating a damp and unhealthy hive environment.

The impact of lower and lower temperatures on a colony can be described as follows:

  • Whilst a colony will generally begin to cluster when ambient hive temperature falls below 18C (64F), the cluster is clearly defined at 14C (57F) internal hive temperature. 
  • Beneath 10C (50F), the colony begins to use increasing levels of energy and stores
At this temperature the cluster is five fold smaller in size and covering far fewer frames

At this temperature the cluster is five fold smaller in size and covering far fewer frames

  • The cluster tightens up to five-fold as the temperature drops to -10C (14F) to reduce the exposed surface area of the colony and ensure bees on the outer edge do not fall beneath 7C (45F) - at 6C (43F) they go into a chill coma.

  • Beneath -10C (14F), the colony can only maintain core temperature requirements by increasing the level of core heat production and consuming increasing levels of stores.
  • Stronger colonies with ample stores are more able to access all the stores available but it is not uncommon to find colonies that have starved, even though full frames of stores are nearby, as the colony was unable to move out of their tight cluster. 
  • There is evidence that particularly strong colonies may even split to access stores.

Knowing the above, wouldn't it be better to provide at least the same insulation as an old oak tree.