White-tailed bumblebee  (Bombus lucorum)

The white-tailed bumblebee (Bombus lucorum) is a common species that is easily confused with the similar species Bombus magnus (3). Work is on-going to determine whether these bees are actually the same species (4). Queens and workers of B. lucorum and B. magnus have bright lemon or creamy yellow stripes with a white tail that may have a pinkish flush. In both species there is a yellow ‘collar’, which is narrower in B. lucorum, but extends below the bases of the wings in B. magnus. Furthermore, the queens of B. lucorum are often small in relation to those of B. magnus (3). There is no known way of distinguishing the males of the two species. They have pure white tails, and a long and uneven covering of hairs. The hair on the face is black, yellow or a mixture of the two colours, and there may also be yellow hair on the thorax (3).

This bumblebee has a wide range, and is known in the Palaearctic, Oriental, Arctic, and western Nearctic regions as well as Japan. It is generally commoner in more northerly regions. It occurs in Iceland, where it has probably been introduced by humans (5). It is widespread throughout Britain, whereas B. magnus is found only in the west and north of Britain (3).

Bombus lucorum is found in a wide variety of habitats, and often occurs in gardens (3). B. magnus is restricted to northerly and western parts of Britain and is associated with upland and moorland habitats (2).

Nests are commonly constructed underground in disused rodent nests, or similar protected positions where there is available material for insulation (2). The queen creates a circular chamber in which she builds a wax egg cell, and she lays her first batch of eggs inside. The eggs are laid on a layer of pollen, which is collected by the queen, and then covered with a layer of wax (6). After hatching, the white larvae are fed on honey and pollen by the queen. When they are fully-grown, the larvae cease to feed and develop into pupae after spinning a protective silk cocoon around themselves. During the pupal stage, the larvae undergo complex changes, and develop into adult workers. Throughout their development, the queen incubates this first brood by lying over the cell in which they grow, keeping them warm with the heat of her body (3), which in turn is produced by the metabolism of sugars derived from the nectar she collects (2).

After emerging, the workers undertake the duties of foraging and nest care, and the queen remains inside the nest, producing further batches of eggs. When the colony reaches its peak, males and new queens are produced. Males develop from unfertilised eggs; after leaving the nest they fly around in search of new queens with which to mate (3). After mating, the new queens search for a place to hibernate. The colony, together with the old queen, gradually dies out in autumn, and the newly mated queens emerge from hibernation the following spring, to establish new colonies (6).

Although this species is not currently threatened in Britain, many British bumblebee species, including this one, have undergone a worrying decline, largely as a result of changes in agricultural practices leading to a loss of open habitats, nesting and hibernation sites, as well as important food plants (2) (8).

Conservation action has not been targeted directly at this species. However, concern over the decline of our bumblebee populations has caused steps to be taken. English Nature has produced a leaflet called 'help save the bumblebee', which includes advice on how to make your garden attractive to bumblebees (8).

English Nature's 'Help save the bumblebee' leaflet is available at:
http://www.english-nature.org.uk/news/news_photo/savegardenbumblesweb.pdf

For more on bumblebees see: Prys-Jones, O.E. & Corbet, S. A (1987). Bumblebees. Cambridge University Press, Cambridge.

Information authenticated by Dr O. Prys-Jones with the support of the British Ecological Society:
http://www.britishecologicalsociety.org/