In the winter, bees hibernate. Not like bears, however, but like penguins. They huddle in a mass and conserve warmth in a tight ball. Bees in the inside of the huddle move to the outside, and vice versa. If it warms up a bit (>50 degrees), and is sunny, they go for a flight and relieve themselves, as healthy bees are unlikely to defecate inside the beehive. They consume honey for energy.
It's amazing to me that honeybees and penguins would use the same technique to stay warm in the winter.
"Honeybees head to the hive when temperatures drop into the 50s. As the weather becomes cool, the honeybees gather in a central area of the hive and form a “winter cluster.” A winter cluster is much like a huddle you may have seen at a football game — except it lasts all winter!
Bees have one main job in the winter — to take care of the queen bee. This means they must keep her safe and warm.
In order to do so, worker bees surround the queen and form a cluster with their bodies. The worker bees then flutter their wings and shiver. This constant motion and continuous use of energy is how the bees keep the inside temperature of the hive warm.
In order to keep shivering, the bees must have enough honey. This is how they get their energy. One of the most important jobs of the beekeeper in the winter is to make sure the honey supply stays full so the bees can keep shivering.
Though the queen is always at the center of the cluster, worker bees rotate from the outside to the inside of the cluster, so no individual worker bee gets too cold. The temperature of the cluster ranges from 46 degrees at the exterior to 80 degrees at the interior. The colder the weather is outside, the more compact the cluster becomes.
In order to produce body heat and stay alive, honeybees must rely on honey for energy. Some studies have found that hives of honeybees will consume up to 30 pounds of stored honey over the course of a single winter. On warmer days, bees will leave the cluster briefly in order to eliminate body waste outside the hive."
http://wonderopolis.org/wonder/what-do-bees-do-in-winter/