Andrena bucephala

Tilcayo Cats original · British Bees · Sources and editorial assessment · Originals retention rule

Andrena bucephala, the big-headed mining bee, is a European bee in the family Andrenidae. In Britain it occurs locally in southern England and Wales. Several females can share one entrance to their underground nests, sometimes forming an aggregation of more than 200 individuals. Despite this shared entrance, it is described as a solitary bee.

Appearance and name

Adults have a forewing length of about 7–10 mm. Females have relatively sparse body hair, with denser pale patches at the sides of the thorax and along the abdominal segments. Their hind legs carry yellow hairs, and the wings have a yellow tint. Males have a conspicuously broad, square head and long jaws.

The species was named by Stephens in 1846. Andrena longipes and A. eximia, both described by Smith in 1847, are treated as synonyms: different scientific names for the same species.

Distribution and habitat

The bee is widespread geographically in Europe but scarce and unevenly distributed. British habitats include open woodland, scrub, gardens and grassland on lime-rich soils. BWARS also records it from parkland and former gravel workings.

The 2016 checklist of British and Irish aculeate Hymenoptera records it from England and Wales. That checklist is a record of the known fauna at publication, rather than a survey of every present-day locality.

Nesting and feeding

There is one generation a year, with adults flying in spring. BWARS gives the main British flight period as mid-April to late May, with occasional records into June.

Nesting groups use a single entrance, often in a steep bank or a rabbit burrow. A nesting site may persist for several years. The arrangement of the tunnels behind the common entrance remains poorly documented; BWARS describes a separate burrow for each female as an assumption, not an established observation.

Females collect pollen mainly from hawthorn and field maple, although adults visit other flowers. The pollen supplies food for the developing young. The cuckoo bee Nomada hirtipes is recorded as a nest parasite, while Stylops aterrimus, a different kind of parasitic insect, can develop in adult bees.

Conservation and research

The British assessment published by Falk in 1991 placed the species in Nationally Scarce A, then called Notable A. This historical designation is still cited in the 2024 genome paper; it should not be read as a new population assessment made in 2024.

In 2024, researchers published a genome assembled from a female collected in Oxfordshire. It contains approximately 380 million DNA base pairs, with almost all the assembled sequence arranged into five chromosome-scale units. This provides a genetic reference for research on the species and its relatives.