Winter condensation and what to do about it.

I use bee cozies on my bees in the winter.  After several several years of using them and not always having enough for all my hives I have seen the difference that having one makes.  They use far less stores to get through the winter, one of the main causes for winter hive death is starvation, sometimes with in inches of stores.  With the cozy on they don't have to cluster as tight and have a better chance of reaching the stores need to stay fed.

Mold from condensation.

The hive wrapped in insulation, the bottom board in place if using SBBs leaves the top to condensate.  All the warm air from the bees is pressed against the uninsulated top cover.  Condensation forms and drips very cold water on to the cluster below causing death and sickness.  A simple fix is to put a piece of insulation in the top airspace.  If you don't have an airspace on the top the next best fix is a nickel under the two front corners of the inner cover to let moister out.