A bee’s winter survival strategy depends entirely on its species and social structure. Social bees, like honeybees, survive winter as an entire colony, using clustering for active warmth. Solitary bees and semi-social bumblebees rely on metabolic suppression (diapause) to survive the cold, often as immature stages or a single queen.
Honeybee Colony Survival (Clustering)
Honeybees do not truly hibernate; they remain active inside their hive throughout the winter. The entire colony survives by forming a dense, dynamic structure called the winter cluster, triggered when the ambient temperature drops below 57°F (14°C). The cluster acts as a single, warm-blooded entity, maintaining a core temperature between 64°F and 93°F (18°C to 34°C). Bees generate this heat by rapidly shivering their flight muscles, a process called thermoregulation. This collective effort is fueled by consuming stored honey, which is converted into metabolic energy.
The cluster is organized into two distinct parts: a tightly packed outer layer called the mantle and a warmer, looser core. Bees on the insulating mantle face inward and compress their bodies to trap air, minimizing heat loss. Individuals continuously rotate between the cold outer shell and the warm inner core to prevent chilling, allowing the cluster to slowly move across the honeycomb to access honey stores.
The Winter Fate of Bumblebee Queens
Bumblebees have a life cycle where only the newly fertilized queen survives the winter. The entire summer colony, including the old queen, workers, and males, perishes in the autumn. The new queen enters a period of true diapause, a state of suspended development and significantly reduced metabolism that can last six to nine months.
During this time, the queen relies exclusively on the substantial fat reserves she built up before the cold arrived. She seeks out a protected location, known as a hibernaculum, to wait out the winter alone. These locations are typically shallow burrows she digs, often going more than four inches (10 cm) deep into the substrate.
Preferred hibernacula include loose, well-drained soil, often on a slope to prevent flooding, or under thick layers of leaf litter, moss, or compost piles. Some queens choose north-facing spots, which stay colder and delay premature emergence by receiving less winter sun. This solitary survival mechanism makes the queen vulnerable, but she is resilient, capable of surviving even short periods of complete submersion under water.
Solitary Bee Diapause Locations
Solitary bees represent the largest group of bee species, and their strategy is distinct: the adult bees die, and the next generation overwinters as immature stages within their natal nests. The overwintering stage is typically a pre-pupa or a pupa, which remains dormant inside a protective cocoon. The specific winter location is determined by the nesting habits of the female bee that laid the egg.
Approximately 70% of solitary bees are ground-nesters, such as Mining Bees. The larvae of these species spend the winter inside individual cells located deep within tunnels excavated by the mother bee in the soil. These nests are typically found in bare, well-drained, or sandy soil that receives sun exposure.
The remaining 30% are cavity-nesters, including Mason Bees and Leafcutter Bees. The developing bees overwinter in a linear series of cells constructed within existing tunnels, such as hollow plant stems or abandoned beetle burrows in dead wood. The larvae remain sealed inside their individual cells until they emerge as adults the following spring.