The Life Cycle Of A Bumblebee Colony

Overwintering of honeybees
A honeybee colony is potentially immortal, and its queen does no foraging. Honeybees overwinter as a cluster of workers around their queen and with a store of honey. During the first warm days of spring these workers emerge from the hive to forage for nectar and pollen with which to feed themselves and to support the development of new workers, building up the colony towards summer. The colony can persist through winter because of the honey store. Workers are therefore present in spring so the queen herself does not need to forage but stays in the hive laying eggs.

Overwintering or hibernation of bumble-bee queens
Bumble-bees do things differently. Unlike honeybees, bumble-bees do not have a perennial nest. Colonies of bumble-bees do not live through the winter as colonies. In autumn the bumble-bee colonies die out and only the young mated queens overwinter (hibernate) by burrowing themselves several centimeters into the soil.

Nest searching and foraging
When the soil temperature rises in spring the queen emerges from hibernation and may be seen foraging on early flowers. At first she forages only for herself, eating large quantities of pollen and nectar while her ovaries develop, and roosting at night under moss and other vegetation. She then seeks a place to establish her nest. The search often ends in the disused nest of a small mammal or bird.

Nest initiation
Having found a suitable site, the queen goes out to collect pollen after she has arranged the nesting material. The pollen is processed into a mass on top of which she builds a cell made of wax in which she will lay her first batch of eggs.

Within convenient reach of the egg clump she constructs a wax honeypot. Taking occasional sips of nectar from this honeypot she broods the egg clump, warming it by contact with the lower surface of her abdomen. During this stage of colony development the queen spends much of her time in the nest, brooding her eggs, and makes only occasional foraging trips.

Colony development
Eggs hatch after 4-6 days. The resulting larvae feed on the pollen mass, and are supplied by the queen with a mixture of nectar and pollen. After 10-20 days the larvae pupate. At this stage the queen will construct one or more new egg chambers, between or on top of the coccoons, in which she lays her second batch of eggs.

Adult workers emerge after after a pupal stage of about 2 weeks as pupae. At first silvery-grey, tousled and soft-winged, the worker acquires her full colours and fluffy appearance after a few hours, and her wings harden within about a day. New workers soon begin foraging, as well as helping the queen to tend the brood. Once there are enough of them to take over foraging duties the queen remains within the nest, where she devotes herself to housework and egg-laying. She will lay batch after batch producing 150 to 400 workers.

Production of males and queens, mating
When the colony is mature some eggs develop not into workers but into males and queens. Both do not take part in the work involved in the colony but leave the nest after a few days. After mating the male bumble-bees die but the young queens will build up a fat body. As an additional food store they fill their highly distensible honeystomach with thick honey. They each then seek a site in which to overwinter.
The overwintered queens will never return to their parental nest to establish a new colony but will search a new, clean nest site.

Colony decline
Queens and males are the colony's contribution to the next generation. They are the last brood to be reared. When they have left, the old nest has no further role to play. The few remaining workers forage only for themselves. Like the males, they will have died off by the end of the season. A new cycle can start.