North of about 55° latitude, honeybee colonies cannot forage or fly for 7–9 months of the year. Instead of hibernating, the whole colony survives by forming a winter cluster — a living ball of bees that generates heat by shivering their flight muscles, with an insulating outer mantle shell packed tight around a warm core where the queen is kept near broodnest temperature. Bees on the outside periodically trade places with bees in the middle so no one freezes for too long.
Individual bees rotate from the cold mantle into the warm core every so often — it can take a bee several hours "queueing" on the surface before it gets a turn to warm back up, which is one reason very small clusters are so vulnerable to arctic cold snaps.
A 3D cutaway of a honeybee hive showing the winter cluster — a living ball of bees that contracts, warms its core and burns through honey stores as outside temperature, colony size, insulation and wind change.
The cluster tightens as it gets colder and windier, the amber core stays near broodnest temperature while the outer mantle tracks closer to ambient, and honey consumption rises with cold, wind and poor insulation but falls as colony size and wrap quality improve.
Drag the outside temperature, colony size, insulation and wind sliders to see the cluster's radius, core/mantle temperatures and honey burn rate respond live. Switch Season to Polar summer forage to see bees fly almost continuously under the midnight sun instead.
Bees on the cold outer mantle periodically swap places with bees in the warm core — a slow-motion queue that keeps any one bee from freezing for too long, which is why very small winter clusters are so much more fragile than large ones.