The Red-shanked carder bee resembles a smaller, rounder, version of the common and widespread Red-tailed bumble bee, Bombus lapidarius, but has red hairs (not all black) on the corbicula. Keys and general biology are found in Sladen (1912), Free & Butler (1959), Alford (1975) and Prŷs-Jones & Corbet (1991).
A medium-sized mining bee, the largest member of the Andrena minutula species-group (subgenus Micrandrena).
A predominantly black bee; the abdomen is narrow and cylindrical, which is probably an adaptation to using small-bore beetle burrows as nest sites. The males have the final segment of the abdomen modified to form a two-pronged peg which is used to hold on inside flowers during the night or in poor weather, which gives a good method for recording the bees under such conditions.
A larger version of the more frequently encountered C. campanularum; of the same general long, thin cylindrical shape, but with distinctive white bands of short hairs on the apices of the abdominal segments.The males also have a two-pronged peg on the final segment of the abdomen and this may be used in the same way as that on the males of C. campanularum. However, I have only ever found males curled up around the base of the stamens of buttercups during poor weather, apparently relying on the closure of the petals to shelter them.
Keys and general biology are found in Sladen (1912), Free & Butler (1959), Alford (1975) and Prŷs-Jones & Corbet (1991). Until recently this species was known as Psithyrus barbutellus, but Psithyrus has now been reduced to a sub-genus within Bombus. It bears a close resemblance to its host, Bombus hortorum, but has an almost circular face, most unlike the very elongated one of B. hortorum.