ed spots.
Bumblebees Nest in a Shed. Image Courtesy Pete Griggs.
Bumblebee nests are first constructed by over-wintered queens in the spring. Upon emerging from hibernation, the queen collects pollen and nectar from flowers and searches for a suitable nest site. The characteristics of the nest site vary among species, with some preferring to nest in underground holes and others in tussock grass or directly on the ground. Once the queen has found a site, she prepares wax pots to store food and wax cells into which eggs are laid. These eggs then hatch into larvae, which cause the wax cells to expand into a clump of brood cells.
These larvae need to be fed both nectar for carbohydrates and protein in order to develop. Bumblebees feed nectar to the larvae by chewing a small hole in the brood cell into which nectar is regurgitated. Larvae are fed pollen in one of two ways, depending on the species. So called "pocket-maker" bumblebees create pockets of pollen at the base of the brood cell clump from which the larvae can feed themselves. Conversely, "pollen-storers" store pollen in separate wax pots and feed it to the larvae in the same fashion as nectar. Bumble bees are incapable of trophallaxis (direct transfer of food from one bee to another) which is common in other hymenoptera such as ants.
After the emergence of the first or second group of workers, workers take over the task of foraging and the queen spends most of her time laying eggs and caring for larvae. The colony grows progressively larger and at some point will begin to produce males and new queens. The point at which this occurs varies among species and is heavily dependent on resource availability and environmental factors. Unlike the workers of more advanced social insects, bumblebee workers are not physically reproductively sterile and are able to lay haploid eggs that develop into viable male bumble bees. Only fertilized queens can lay diploid eggs that mature into workers and new queens.
Early in the colony cycle, the queen bumblebee compensates for 