Honey Bee Winter Survival
As colder temperatures arrive, honey bees form a winter cluster. When outside temperatures drop below approximately 50-57°F (10-14°C), worker bees gather tightly around their queen and any developing brood. This collective huddle acts as a living, insulating sphere, with outer bees packing closely to retain heat.
To generate warmth, honey bees rapidly vibrate their flight muscles without moving their wings. This muscular activity produces heat, shared among the bees. The queen bee remains at the cluster’s center, where the temperature is maintained at a consistent 90-100°F (32-38°C) if brood is present.
The cluster constantly adjusts its size and density in response to external temperatures, tightening when colder and loosening as it warms. Throughout winter, the colony relies on stored honey as its fuel source for heat generation. A strong, healthy colony with ample honey reserves, ideally 60-100 pounds for northern regions, is important for survival through cold months.
Other Bee Species’ Winter Survival
Unlike honey bees, most other bee species do not maintain large, active colonies through winter. Bumblebees have an annual life cycle where the entire colony, including workers, males, and the old queen, perishes with the onset of cold weather. Only newly mated queens survive, seeking sheltered spots for hibernation. These queens burrow into soft, well-drained soil, leaf litter, or hollow trees, often at depths of 5-15 cm. During this dormant state, they produce glycerol to prevent freezing.
Solitary bees also have distinct overwintering strategies. Many do not survive as adults through winter; instead, they lay eggs in sealed nesting cells during warmer months. These eggs develop into larvae or pupae, which then enter a state of torpor within protective cocoons or nesting tunnels. Depending on the species, they might overwinter as fully developed adults inside their cocoons, ready to emerge in spring, or as larvae that will pupate in spring. Nesting sites can be hollow plant stems, ground tunnels, or holes in wood.
Returning to Activity
As spring approaches and temperatures rise, bees emerge from their winter states. Honey bee clusters gradually expand, and the queen increases egg-laying, leading to a rapid increase in colony population. Worker bees forage for nectar and pollen, essential for feeding the growing brood and replenishing hive stores. Increased activity at the hive entrance and bees returning with pollen indicate renewed vigor.
Bumblebee queens, having survived winter hibernation, emerge in early spring to establish new nests. They seek early spring flowers to replenish energy reserves before searching for suitable nesting sites like abandoned rodent burrows or dense vegetation. Once a site is chosen, the queen lays eggs and forages for her first brood, working alone until her first offspring develop into worker bees.
Solitary bees, having overwintered as larvae or pupae, complete their development and emerge as adults when conditions are favorable. These newly emerged adults immediately begin their life cycle, seeking mates and suitable nesting locations to lay eggs. The timing of emergence varies by species, with some appearing in early spring and others later in summer, depending on their development stage.
Supporting Bees During Cold Months
Supporting bees through cold months involves several practical actions. Leaving undisturbed natural areas, such as leaf litter and dead plant stems, provides overwintering sites for bumblebee queens and solitary bees. Bumblebee queens hibernate in leaf litter or underground, while many solitary bees develop within hollow stems or ground tunnels. Delaying garden cleanup until late spring allows these bees to safely emerge.
Planting winter-flowering or early spring-blooming plants offers early food sources for emerging bees. Flowers like crocuses, dandelions, and certain willow species provide nectar and pollen when other food sources are scarce. Ensuring a continuous succession of blooms throughout the season helps maintain a steady food supply.
Providing undisturbed areas, such as log piles or un-tilled soil, creates additional nesting and overwintering habitats. Avoiding pesticides, especially on flowering plants, protects bees from harmful chemicals.