The term “bee” encompasses thousands of species, meaning there is no single answer to how they survive winter. Survival depends on the bee’s social structure, dividing species into two groups: social colony-dwellers (like the honey bee) and solitary species (such as mason bees and the semi-social bumble bee). Both groups must contend with freezing temperatures and the absence of flowering plants, but their survival methods are fundamentally distinct.
The Fall Shift: Preparation for Cold Weather
As the summer nectar flow wanes, all bee species begin a physiological and behavioral transition to prepare for the coming cold. For colonial species, this period involves resource consolidation and a change in the caste system. Worker bees aggressively stockpile honey, aiming for a minimum of about 40 pounds of stored carbohydrates to fuel the colony through the winter months.
The queen bee naturally reduces her egg-laying rate as daylight hours shorten, leading to a dramatic reduction in the amount of brood that needs warming. The colony also begins rearing “winter bees.” These bees are physiologically distinct from their summer counterparts, possessing higher fat reserves and a much longer lifespan, sometimes living for several months instead of just a few weeks.
Finally, the colony expels the male drones from the hive. Since drones are non-foraging resource consumers whose reproductive function is no longer needed, their removal ensures stored honey is reserved exclusively for the surviving workers and the queen.
Social Bees: The Honey Bee Huddle
Honey bees (Apis mellifera) are the only species where the entire colony, including the queen, survives the winter by remaining active inside their nest cavity. When the ambient temperature drops to approximately 57°F, the bees form a tight, communal sphere known as the winter cluster. The location of this cluster shifts slowly over the winter, always following the dwindling supply of honey stores within the hive.
The cluster operates as a “superorganism” with distinct layers to maintain warmth. The outer layer, or mantle, consists of densely packed bees that form an insulating shell, minimizing heat loss to the cold air. These outer bees face inward and may allow their abdomens to cool significantly, but they constantly rotate with the warmer bees from the interior to prevent any individual from freezing.
Heat generation occurs in the cluster’s core, where bees rapidly vibrate their flight muscles without moving their wings. This muscle activity burns stored honey to generate warmth (thermogenesis). They regulate the core temperature to be consistently above 68°F, even when outside temperatures are well below freezing. If the colony has started rearing new brood in late winter, the bees will expend even more energy to raise the core temperature to a steady 91 to 95°F to ensure the survival of the developing young.
Solitary and Bumble Bees: Survival Through Hibernation
The vast majority of bee species, including solitary bees and bumble bees, cannot survive the winter as a full colony. For these species, the life cycle concludes with the first hard frost, leading to the death of all adult workers, drones, and the old queen. The continuity of the species rests solely on the newly mated queens, often called gynes in the case of bumble bees, which are the only individuals to overwinter.
These solitary survivors seek sheltered spots to enter a deep state of metabolic dormancy called diapause. Bumble bee queens, for example, typically burrow into loose soil, compost piles, or thick leaf litter, creating a small, insulated chamber called a hibernaculum. Solitary bees, such as mason bees, often overwinter inside their larval cocoons within the tunnels they were born in, which might be in hollow stems or wooden cavities.
During diapause, the queen’s metabolic rate is severely reduced, allowing her to survive for six to nine months without food or movement. Bumblebee queens further protect themselves from freezing by synthesizing high concentrations of glycerol, a substance that acts as an antifreeze to protect their cells and organs from ice crystal damage. They remain in this dormant state until the first warm temperatures of spring signal the time to emerge and begin founding a new colony alone.