What the bees are doing...
As winter hits and they heat their hive, the bees insulate against the drafts and fill those little holes with propolis, a sticky wax-like resin that they get from trees. This also helps to keep out robber bees and mice. Later, when collected from the hive, propolis has been used for a variety of medicinal purposes including soothing allergies, sore throats and ulcers.