Bees in the Dead of Winter

A lot of people don't really think about what honeybees do in the wintertime. Many think that they simply die off or hibernate. That couldn't be further from the truth. Scientists are still discovering the complexities of honeybees and their techniques for surviving the coldest of winters, all while keeping their queen at a balmy 94 degrees fahrenheit inside the hive.

When temperatures start to fall, the bees start to cluster in their hive. Meanwhile, the queen stops laying eggs in late fall and early winter since food stores are limited. 

Thermal Image of a Hive in Winter

To insulate the colony as outside temperatures drop, the honeybee workers form a cluster around the queen and the brood (immature bees, from eggs to larvae) to keep them warm. The bees in the cluster keep their heads pointed inward, and the bees on the inside of the cluster feed on the honey that’s been stored in the hive for the winter. Those on the outside of the cluster insulate their companions inside the sphere of honey bees.

When the temperature reaches about 57 degrees Fahrenheit, the cluster tightens and the bees remain relatively motionless. The combined body heat that’s generated (more details below) by the bees lined up side-by-side in the outer ring of the cluster is sufficient to keep the colony warm.

The cluster can also expand or contract as temperatures fluctuate. As ambient temperatures rise, the bees on the outside separate a bit to increase the air flow through the cluster. As temperatures fall, the cluster tightens as the outer workers pull together.

As temperatures continue to drop, the worker bees start actively generating heat within the hive. They begin to flex the flight muscles located within the thorax of their bodies. But their wings don’t move. Instead, this vibration raises each bee's body temperature. With thousands of bees vibrating in this manner, the temperature at the center of the cluster warms to a cozy 93 degrees Fahrenheit.

During warmer spells, the entire cluster will move within the hive, positioning themselves around fresh supplies of nectar or other sugar sources.

About 40% of honeybee colonies die out every year.  Most of the mortality occurs in the wintertime.  However, with the right resources and strength, colonies can make it through the winter and begin a rapid growth trajectory in mid to late April here in Michigan.  Beekeepers can play a significant role in the survival of their honeybee colonies by helping to manage varroa mite loads, (mites that prey on honeybee larvae and also transmit diseases), ensure that colonies have adequate food stores going into winter and also aiding by providing adequate shelter for the colonies.

Honeybees have many challenges but responsible beekeepers can really improve their chances for survival with just a few interventions.  If you'd like to continue learning, More information will be coming soon!

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