| | Insects of Britain and Ireland: the bumblebees and cuckoo bees (Bombus and Psithyrus) |
Tree Bumblebee.
Biology. Social insects forming organized communities; the larvae feeding on pollen and nectar gathered and prepared by the adult females.
Adult morphology. Adult queens, workers and males all similar appearance. Adults about 13–19 mm long (queens about 18 mm, workers 14 mm, males 16 mm). Face relatively short; at least as wide as long, or wider. The facial hairs of males black; vertex black haired. The facial hairs of females black; vertex black haired. The mandibles of the females round-ended, not oblique. Thorax predominantly ginger-haired; not banded (homogeneously bright orangy-ginger haired). The outer surface of the hind tibiae of females with a conspicuous ‘pollen basket’, in the form of an elongate, shiny, hairless, area framed by stout hairs. The hind tibiae of the males having a fringe of long hairs along the outer margin. Scutellum of females at least partly pale-haired.
The abdomen black apart from the conspicuous white tail. Abdomen conspicuously patterned; with a contrasting tail. The tail white. Abdomen without conspicuous banding between the anterior of the tail and the thorax. Sternite 6 of females without a median keel.
Male genitalia. The sagittae rather straight to curved inwards around the spatha; smooth to the base, neither serrate nor dentate nor hooked externally; apices apically turned inwards and conspicuously sickle-shaped. The ends of the claspers not expanded; dark and horny; not or only slightly emarginate, without teeth; with the volsella inconspicuous (fairly).
British representation. Recorded from England and Wales. Only recently recorded in the U.K, but seemingly spreading: now widespread in England north to Hertfordshire and northeast to Northumberland, as yet absent from northwest England, Wales, Scotland and Ireland. The adults abroad during March to August (females), April to August (males). A species of woodland and urban habitats in mainland Europe, in Britain most often recorded in gardens.
Illustrations. • Male genital capsules of Bombus and Psithyrus. Male genital capsules of Bombus and Psithyrus, routinely displayed as viewed from below. 1–5, PSITHYRUS. 1, P. rupestris; 2, P. vestalis; 3, P. barbutellus; 4, P. campestris; 5, P. sylvestris. 6–17, BOMBUS. 6, B. muscorum; 7, B. humilis ssp. anglicus; 8, B. pascuorum; 9. B. hortorum; 10, B. subterraneus ssp. latreillellus; 11, B. sylvarum; 12, B. ruderarius; 13, B. pomorum; 14, B. lapidarius; 15, B. pratorum (cf. B. HYPNORUM, B. jonellus and B. monticola); 16, B. soroeensis; 17, B. terrestris. Adapted from Saunders (1896), the nomenclature updated.
We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa. See also Guidelines for using data taken from Web publications.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. Insects of Britain and Ireland: the bumblebees and cuckoo bees (Bombus and Psithyrus). Version: 27th July 2019. delta-intkey.com’.
