Bees, like many insects, exhibit adaptations to survive colder temperatures. Their strategies vary significantly across different species, showcasing diverse approaches to enduring periods when resources are scarce. These adaptations allow them to persist, ensuring the continuation of their populations through winter.
Honey Bee Winter Behavior and Survival
Honey bee colonies do not hibernate; instead, they remain active inside their hives throughout the winter. To combat the cold, worker bees form a tight cluster when outside temperatures drop below 50-57°F (10-14°C). This cluster acts as a collective organism, with bees on the outer layer packing tightly together to create an insulating mantle, while those in the core remain more loosely packed, allowing for movement.
Within this cluster, honey bees generate heat by rapidly vibrating their flight muscles, similar to shivering. This activity consumes energy, which they obtain from honey stores collected during warmer months. The queen bee is typically located at the cluster’s center, where the temperature is maintained at a warm 90-100°F (32-38°C) for her survival.
Bees on the outer, colder layer of the cluster periodically rotate with those in the warmer core, ensuring no individual bee becomes too cold. This continuous exchange helps regulate the overall cluster temperature and distributes the energetic burden. The cluster will contract and tighten further as external temperatures drop, becoming more compact to conserve heat.
The queen’s egg-laying activity reduces or halts during the coldest parts of winter to conserve resources. As winter progresses and daylight hours lengthen, she may gradually resume laying eggs, particularly those that will develop into “winter bees.” These specialized bees possess larger fat bodies and a longer lifespan, often living up to six months compared to the typical six-week lifespan of summer worker bees.
Preparing for the Cold Season
Honey bee colonies begin preparations for winter in late summer and autumn. A primary activity during this period is extensive foraging, where worker bees collect nectar and pollen. This gathered nectar is converted into honey, serving as the primary energy source for the colony’s survival through winter.
As autumn progresses, a change occurs within the hive: the expulsion of male drones. Drones, whose role is to mate with the queen, are resource-intensive and do not contribute to the colony’s winter survival. Worker bees cease feeding them and force them out of the hive, where they perish from exposure or starvation, conserving food stores for the rest of the colony.
The colony also focuses on maintaining the structural integrity of the hive. Bees repair any damage and may reduce the size of the hive entrance to help with temperature regulation and deter pests seeking warmth. A strong, well-populated colony with sufficient honey reserves is better positioned to endure the winter challenges.
Winter Strategies of Other Bee Species
While honey bees overwinter as a colony, many other bee species employ different survival mechanisms. Solitary bees, which do not live in colonies or produce honey, typically overwinter as immature stages, such as larvae or pupae. These developing bees are housed within protective cocoons or cells in nests constructed by their mothers during warmer months.
These nests are often located in sheltered environments like underground burrows, hollow plant stems, or tunnels in dead wood. The larvae or pupae remain dormant through the cold season, relying on the food provisions (often a mixture of pollen and nectar known as “bee bread”) left by the female bee. They complete their development and emerge as adults when temperatures rise in the spring.
Bumblebees also exhibit a distinct winter strategy compared to honey bees. Entire bumblebee colonies, including the worker bees and male drones, die off with the onset of cold weather. Only the newly mated queen survives the winter.
Before winter, these new queens consume nectar and pollen to build fat reserves. They find a solitary, protected location, often burrowing underground in a small chamber called a hibernaculum. The queen enters a state of hibernation, where her metabolism slows down, allowing her to survive without food until she emerges in spring to establish a new colony.