Most bumblebees, unlike honeybees, die in the fall. Only the young, fertilized bumblebee queens overwinter. When they emerge early in the spring, each must start a new colony, with no help from worker bees. The queen builds a ball of moss, hair or grass, often in an abandoned rodent nest or small cavity. Within this ball the queen builds a wax honey pot, and provisions it with nectar from early-blooming flowers. Next, she collects pollen and forms it into a mound on the floor of her nest. She then lays eggs in the pile of pollen, and coats it with wax secreted from her body.
The queen bumblebee keeps her eggs warm by sitting on the pollen mound, and by shivering her muscles, raising her body temperature to between 98° F. and 102° F. For nourishment, she consumes honey from her wax pot, which is positioned within her reach. In four days, the eggs, all of which will become female workers, hatch. The bumblebee queen continues her maternal care, foraging for pollen and nectar to feed to her larvae until they pupate. After this first brood emerges as adult bumblebees the queen concentrates her efforts on laying eggs. Unfertilized female worker bees raise the larvae and the colony swells in number. At the end of summer, new queens (females) and males are produced in order to allow the colony to reproduce. After the new queens mate and become fertilized, the males all die, along with the female worker bees. The queen then seeks shelter for the winter. (Photo: Tri-colored Bumblebee queen collecting Trailing Arbutus nectar or pollen)
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