The general life cycle of the bumble bee differs a bit in different parts of the U.S., but in the Northeast the life cycle is as follows. Only new queens (produced at the end of the summer) overwinter. In the late summer and fall they mate (the males die) and the queens feed heavily on late summer and fall flowers such as asters and goldenrods. The queens then seek out protected overwintering sites in stonewalls and fallen trees. Many of these sites are in the forest edge. In the early spring, queens emerge from their overwintering sites and search for nest sites. Nest sites are often abandoned rodent or rabbit burrows that the queens find by smell. The queens lay fertilized eggs, incubate them and keep them warm with their body heat. When the eggs hatch, the queens forage for pollen and nectar on early spring flowering trees and shrubs and early blooming herbaceous wild flowers. The queen raises her daughters through several larva stages, a pupa stage and upon completion of this stage they metamorphose to worker bees, in a month to a month and a half. These workers are generally very small as the queen was only able to provide them with limited food. With the first batch of mature daughters the queen forages less and less and instead stays in the nest and rears more daughters. The mature daughters become the foraging force. Throughout the summer more mature daughters emerge and so the colony grows in numbers and the workers also become larger as their food limitation becomes less. By mid summer, the queen not only lays eggs destined to become daughters, but also lays eggs that will become males or drones. The late summer males and females that emerge leave the nest and mate. The males die and the large females which are destined to become next years queens feed heavily in preparation for hibernation in overwintering sites. The old queen does not usually live past the late summer or fall.
– Frank Drummond, University of Maine