British Insects: Bumblebees and Cuckoo-bees


L. Watson and M. J. Dallwitz

Bombus sylvarum (Linnaeus)

Subspecies distinctus Vogt (nigrescens Pérez).

Subgenus. Subgenus Thoracobombus.

Biology. Social insects forming organized communities; the larvae feeding on pollen and nectar gathered and prepared by the adult females. Nesting on the surface of the ground, or only just below.

Adult morphology. Adult queens, workers and males all similar appearance. Adults about 12–28 mm long (queens about 17 mm, workers 14 mm, males 13 mm). Face relatively short (that of the male clothed with pale hairs); somewhat longer than wide. The facial hairs of males greenish yellow, or greyish intermixed with black; vertex with greyish hairs intermixed with black ones. The facial hairs of females greenish yellow, or greyish intermixed with black (cf. Saunders); vertex with greyish hairs intermixed with black ones. The clypeus of females with scattered large to medium punctures over most of its surface, including much of the central area. The mandibles of the females round-ended, not oblique. Antennae of the male with the third segment shorter than the fifth (much shorter); with the third segment equalling or only slightly longer than the fourth (5th approximately as long as 3rd and 4th together). Thorax not predominantly ginger-haired; usually banded (usually yellowish-greenish-greyish fore and aft, rarely all black in dark forms); usually black across the middle, with pale anterior and posterior bands (the pale posterior band in females wider in the middle than laterally); the light thoracic hairs yellowish grey, or greenish grey, or dirty yellowish. 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; pollen basket framed by red or orange-red hairs. The hind tibiae of the males having a fringe of long hairs along the outer margin. Mid basitarsus of females with the distal-posterior margin extended to form a sharp angle of less than 45 degrees, or produced into a narrow tooth or spine. Scutellum of females at least partly pale-haired. Scutellum of males pale- or predominantly pale-haired.

The abdomen black, with a narrow pale band adjacent to the thorax (tergites 1 and 2), and another adjacent to the shortly orange-red tail. Abdomen conspicuously patterned; with a contrasting tail. The tail orange-red (in females over tergites 4–6, i.e. over less than half the length of the abdomen, pale greenish grey over tergite 1). Abdomen conspicuously banded between the anterior of the tail and the thorax; with a pale band adjacent to the thorax (this pale greenish or yellowish grey). Tergite 2 of females pale greenish grey with traces of black laterally. Sternite 2 of females with a weak rounded transverse ridge between the anterior and posterior margins.

Male genitalia. The sagittae curved inwards around the spatha; smooth to the base, neither serrate nor dentate nor hooked externally; apices apically turned outwards, obliquely truncate and minutely hooked externally at the tip. The ends of the claspers much expanded; dark and horny; conspicuously emarginate and toothed; with the volsella readily visible at their ends (at least as a small terminal hook).

British representation. Recorded from England, Wales, and Ireland. Recorded from sites in the southeast of England and Wales, and in southern Ireland. The adults abroad during April to October (females), or July to October (males).

Illustrations. • British Bombus spp. (1): Saunders. • Male genital capsules of Bombus and Psithyrus.

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Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: Bumblebees and Cuckoobees. Version: 1st January 2012.’.