The question of where bees go when temperatures drop depends entirely on the species. Bees represent a vast group of insects with survival mechanisms ranging from complex social cooperation to complete individual dormancy. The method a bee uses to survive the cold is tied to its social structure, dividing strategies between perennial colonies and those species whose life cycle ends with the first hard frost. This determines whether they rely on collective warmth inside a hive or a deep, solitary sleep in a protected location.
The Honey Bee Strategy: Winter Clustering
Honey bees are the only common species to maintain a colony year-round, surviving winter by remaining active inside their hive. They do not hibernate; instead, they engage in collective thermoregulation known as the winter cluster. This cluster forms when the ambient temperature drops below approximately 57°F, causing the bees to huddle together in a dense ball.
The cluster operates as a unified organism designed to conserve and generate heat. It consists of a tightly packed outer mantle of bees that acts as insulation, while the core bees are more loosely arranged. The queen resides safely at the cluster’s center, the warmest part of the formation.
To produce warmth, worker bees in the core rapidly vibrate their thoracic flight muscles in a process called shivering thermogenesis. This muscle activity generates metabolic heat without requiring flight. The bees constantly rotate, with individuals moving from the cooler outer mantle into the warmer interior to prevent any single bee from succumbing to the cold.
When the colony is broodless, the cluster’s core temperature is maintained around 70°F. If the queen begins laying eggs, the bees must increase heat output to maintain the brood nest at a constant 93°F. The colder the outside air becomes, the more the bees contract the cluster, making the mantle denser and minimizing the exposed surface area.
Solitary and Bumble Bees: Surviving Alone
Most bee species, including solitary bees and bumble bees, follow a less social survival plan involving metabolic dormancy. For bumble bees, the entire colony, including all workers and the founding queen, dies as the weather turns cold. Only the newly mated, young queens, called gynes, survive to start a new colony the following spring.
These young bumble bee queens seek insulated, protected locations to spend the winter, often burrowing into soft soil, under leaf litter, or finding refuge in sheltered cavities. Once settled, the queen enters diapause, a condition where her metabolism slows drastically, allowing her to survive for months without food. This state of true hibernation is triggered by shortening day length and dropping temperatures.
Solitary bees, which make up most of the world’s bee diversity, also rely on dormancy, but their survival centers on the next generation. Adult solitary bees active during the summer complete their life cycle and die before winter. The bee survives the cold months as a fully developed larva or pupa inside its natal nest.
The offspring are sealed within specialized cells, often constructed in tunnels bored into wood, hollow plant stems, or deep underground in soil nests. They remain in a state of suspended animation within these protective chambers. The insulation helps shield the developing bee from temperature fluctuations until the warmth of spring triggers their emergence.
Fueling Survival: Winter Food Stores
The ability of any bee species to survive winter, whether through clustering or dormancy, depends on a dedicated fuel source. For the honey bee cluster, the fuel is stored honey, a concentrated source of carbohydrates. The muscle vibration required for thermogenesis continuously burns through these sugar reserves over the cold months. A typical colony needs a significant volume of honey stores to sustain its collective warmth, often consuming between 33 and 110 pounds depending on the winter’s severity. If the cluster cannot reach the honey during a cold spell, the entire colony can quickly starve.
The survival of solitary and bumble bee queens relies on internal fat reserves, not stored honey. In the late summer and fall, the newly mated bumble bee queen forages intensely to build up large quantities of adipose tissue. This fat acts as a biological battery, slowly metabolized to power her body’s minimal functions throughout diapause.
Solitary bee larvae survive on a dedicated food package provisioned by their mother. Before sealing the nest cell, the mother deposits a ball of “bee bread,” a mixture of pollen and nectar. This nutrient-rich provision is the only food the larva consumes, sustaining its development and providing the energy needed to survive its dormant state until it emerges as an adult the following spring.