There are anything between 20,000 and 30,000 bee species in the world. Britain has 254 species, 24 of them are bumblebees. It is estimated that a third of all human food depends on the pollination services of bees!

Buff-tailed Bumblebee

Bumblebees

Bumblebees are social and live in colonies. When fully developed, each colony comprises a single, egg-laying female, the queen, and a number of sterile females called workers.

Female nesting bees are able to find their way back to their nests by memorizing landmarks and through sun-compass orientation. A female bee memorizes the position of the sun when she leaves her nest. Using this and an inbuilt clock to compensate for the sun's movements she is able to navigate back to her nest, even if the sun is obscured by clouds.

After a female has found a suitable nest site, she makes several orientation flights. These have a characteristic looping from side to side around the nest entrance. She is memorising landmarks close to the entrance, such as plants or stones. Later she broadens the sweep of her loops as she memorizes more distant landmarks, such as an isolated tree or shape of a hill. Experiments have shown that some British garden bumblebees can return to a nest from distances over 6km.

Bumblebees have a pollen basket in a specially adapted hind leg where the bee builds up a dense mass of pollen, slightly moistened with nectar. The bumblebee then transports this back to the nest, where she deposits the pollen into a wax storage pot using her middle legs.

There are six bumblebee species which are widespread and common in gardens in Britain, central and northern Europe. These are: Bombus terrestris (Buff-tailed Bumblebee) and its close relative B. lucorum (Common White-tailed Bumblebee), which are the two most likely species to use your nest; B. pratorum (Early Bumblebee) and B. lapidarius (Common Red-tailed Bumblebee); B. pascuorum (Common Ginger Bumblebee) and B. hortorum (Common Long-tongued Bumblebee). In central and northern Europe, a seventh species may occur. This is B. hypnorum, a gingery species with a distinct white tail. In North America there are about 46 species of Bumblebees that have to date been persuaded to nest in boxes similar to this. The commonest are: Bombus terricola, B. fraternus, B. nevadensis, B. fervidus and B. pennsylvanicus.

Small Garden Bumblebee