As colder temperatures arrive, many wonder how bees survive the winter months. Bee species employ diverse strategies to endure the cold, ranging from communal warmth to solitary hibernation.
Honey Bees’ Winter Survival Strategies
Honey bee colonies remain active throughout the winter. They do not hibernate but form a dense cluster inside their hive to generate and conserve warmth. Worker bees rapidly vibrate their flight muscles, without flying, to produce heat, much like a furnace. This collective shivering allows them to maintain a core temperature of around 90-100°F (32-38°C) within the cluster, even when outside temperatures drop significantly.
The queen bee is typically at the warm center of this cluster, surrounded by worker bees. Bees on the outer layer are packed tightly to insulate the group, while those in the core move more freely. As the hive’s internal temperature fluctuates, the cluster expands or contracts to regulate warmth, with bees rotating from the outer layer to the warmer interior. Their survival depends on consuming honey, stored during warmer months, as their primary energy source to fuel this heat generation.
How Other Bee Species Survive Winter
While honey bees huddle, most other bee species adopt different winter survival strategies. Bumble bee colonies are annual, meaning the entire colony perishes with the onset of cold weather. Only new, mated queen bumble bees survive winter by hibernating. These queens find sheltered spots, such as underground burrows, under leaf litter, or within wood piles, where they remain dormant until spring.
Solitary bees, which make up the majority of bee species, have overwintering methods where adults die before winter. Their offspring survive the cold in various developmental stages, often within protective cocoons inside nesting tunnels. Some species overwinter as larvae, feeding on stored pollen and nectar, while others develop into adult bees within their cocoons but remain dormant until spring. These nesting sites can be in hollow plant stems, in the ground, or in pre-existing cavities.
Winter Challenges for Bees
Winter presents numerous challenges for all bee populations. Extreme cold is a direct threat, as prolonged low temperatures can lead to colony losses if bees cannot maintain sufficient warmth or if their insulating cluster is disrupted. The scarcity of natural forage is another challenge, as flowering plants providing nectar and pollen are absent during colder months. Bees must rely on stored provisions or fat reserves, making preparation during warmer seasons important.
Pests and diseases also pose a threat during winter. For honey bees, Varroa mites are a concern, as these parasites weaken bees and transmit viruses, increasing colony mortality. Colonies with high mite loads or existing health issues are less likely to survive. Habitat loss and human disturbance can also reduce available nesting sites and food sources, making winter survival more difficult for wild bee species.
How to Help Bees During Winter
Supporting bee populations through winter involves several steps. One method is to leave garden debris, such as dead plant stems and leaf litter, undisturbed throughout colder months. This provides shelter and insulation for hibernating queen bumble bees and the overwintering larvae or adults of solitary bees. Avoiding autumn garden tidying benefits these hidden residents.
Planting early-blooming flowers is another way to support bees as they emerge from winter dormancy. Species like crocus, hellebore, and mahonia can provide nectar and pollen sources when other food is scarce in late winter and early spring. For honey bees, beekeepers can ensure hives have sufficient honey stores and consider supplemental feeding if necessary. Minimizing disturbance to known bee nests or hives during winter helps their survival.