The exceptionally long tongue of this species allows it to obtain nectar from plants with deep-tubed flowers, which honeybees and other bumblebees cannot exploit (5). It is an important pollinator of fruit trees and clover, and also visits deadnettle, foxgloves, cowslips and a range of other plants (4). Colonies contain between 50 and 120 insects, and are present between late April and early October (2). The queen is the only member of a colony to survive the winter, they emerge in April and begin to search for a suitable place in which to establish a nest (7). Nests are typically made underground, in banks and among tree roots (2), or occasionally above ground in bird boxes (7). 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 (5). 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. 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. In this species, males are present between June and October, but their numbers peak towards the end of July (2). After mating, these new queens search for a place to hibernate. The colony and the old queen gradually die, and the newly mated queens emerge the following spring, to establish new colonies (5).
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