mperature, via solar radiation, internal mechanisms of "shivering" and cooling from the abdomen (called heterothermy).
Bumblebee colonies are usually much less extensive than those of honey bees. This is due to a number of factors including: the small physical size of the nest cavity, a single female is responsible for the initial construction and reproduction that happens within the nest, and the restriction of the colony to a single season (in most species). Often, mature bumblebee nests will hold fewer than 50 individuals and are typically found below ground (Figure 43). They sometimes construct a wax canopy over the top of their nest for protection from moisture and insulation. Bumblebees do not often preserve their nests through the winter, though some tropical species live in their nests for several years (and their colonies can grow quite large, depending on the size of the nest cavity). In temperate species, the last generation of summer includes a number of queens who overwinter separately in protected 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 larva