About Bombus barbutellus (Kirby, 1802)
This is a medium-sized bumblebee species. Females reach a body length of 18 mm (0.71 in), while males measure 15 mm (0.59 in). The collar and top of the head are yellow. Yellow hairs are present on the scutellum, and this marking is particularly visible on males. The first abdominal segment, or first tergite, is usually more or less yellow. The tail is whitish, but the last tergite of males has intermixed black hairs. All remaining body fur is black, and the fur is quite short, especially on old queens that have finished hibernation. This species is widely distributed across most of Europe, though it is not particularly common there. Its range extends from central Fennoscandia in the north down to southern Spain, and from the British Isles in the west to far eastern Russia. Within Britain, it is mostly found in southern England, East Anglia, and western Wales. As a cuckoo bumblebee, Bombus barbutellus does not build its own nest. Instead, it usurps the nests of other bumblebees: it kills the host nest's queen, and forces the host workers to raise its own offspring. Its main host species are Bombus hortorum, Bombus ruderatus, and Bombus argillaceus. Its preferred food sources are flowering plants including thistles. Queens also feed from white deadnettle and vetches, while males feed from bramble, knapweed, lavender, and honeysuckles.
