Bumble bees, like many other insects, enter a state of dormancy known as hibernation to survive harsh winter conditions. This article explores where bumble bees spend their winter months, ensuring their survival until warmer weather returns.
The Hibernating Bumble Bee
Only new, fertilized queen bumble bees hibernate during colder months. As autumn progresses, the rest of the colony—worker bees, male drones, and the old queen—die off, leaving only new queens to carry on the species.
This dormancy typically begins in late autumn or early winter and lasts until early spring, varying by local climate and species. Hibernation allows the queen to endure food scarcity and extreme cold, enabling her to emerge in spring to establish a new colony.
Preferred Hibernation Spots
Queen bumble bees seek specific underground locations, known as a hibernaculum, for winter dormancy. These spots provide shelter and stability, protecting them from temperature fluctuations, predators, and disturbances. Queens often burrow several centimeters deep into loose or soft earth.
Old rodent burrows also serve as suitable hibernacula. Queens may also be found near tree roots, where the soil offers stability and insulation. These subterranean locations maintain a consistent temperature, preventing freezing or overheating.
Beyond underground sites, queens find shelter beneath thick layers of natural debris. Dense leaf litter, deep moss, or thick clumps of grass provide insulation and concealment, shielding the queen from winter elements.
Other sheltered spots include compost piles, which generate warmth from decomposition, or gaps within log piles. Queens might also utilize protected spaces under rocks. These sites are typically cool, dark, well-drained but not completely dry, and offer protection from the elements.
Preparing for Winter Sleep
Before hibernation, the new queen bumble bee undergoes a preparation phase. After mating, she feeds intensively on nectar and pollen, building substantial fat reserves.
These fat reserves are her sole energy source throughout winter. Once sufficient, the queen departs her natal nest. Her search for a suitable hibernaculum can be extensive.
Finding the ideal, sheltered location is critical for her survival. The queen often flies considerable distances to locate a spot that meets the necessary criteria for protection and stability. This careful selection helps ensure she can endure the long winter.
The Return of the Queen
As spring approaches and ambient temperatures begin to rise, the queen bumble bee emerges from her hibernaculum. Her emergence is often triggered by the warming soil and the increasing daylight hours. The queen, having survived the winter on her stored fat reserves, is initially quite sluggish and requires immediate sustenance.
Her first priority upon emerging is to locate early spring flowers, such as crocuses, willows, or dandelions, to feed on their nectar and pollen. This crucial feeding period helps her regain energy and build strength after her long dormancy. Once sufficiently energized, the queen begins her search for a suitable nesting site. She will then establish a new colony, laying eggs and raising the first generation of worker bees for the new season.