Sharp-collared furrow bee

How to recognise it

Small, dark and slender at 7-9 mm, with pale hair bands across the abdomen and a distinctly sharp-edged collar to the thorax. Easily dismissed as a fly at a glance.

• Small, dark and banded, with a sharply defined thoracic collar.
• Nests in dense aggregations in firm bare soil, often with hundreds of entrances in a few square metres.
• A guard bee frequently visible in the entrance, head blocking the hole.
• Flies April to September in southern and central Europe.

Body length 7–10 mm (typically 8 mm).

Biology

Social organisation

Primitively eusocial

Social behaviour without the sharp physical caste separation of honey bees — the queen looks much like her workers. Some sweat bees.

Colony size at peak

5–30 individuals

Colony lifespan

One season.

Winter

Mated females overwinter alone in the ground and found nests in spring. There is no overwintering colony.

Castes

Foundress, Workers, only slightly smaller than her, New reproductive females, Males

Nesting

Burrows in the ground

Digs a burrow in firm bare soil, frequently in very dense aggregations. The foundress or a worker guards the entrance with her head blocking the hole, admitting nestmates and excluding parasites — behaviour easy to watch and among the clearest signs of sociality in a small bee.

Carries pollen

Scopa — dense hairs on the hind leg

On the wing

April to September

Lifecycle

1. 1Spring foundationAn overwintered mated female digs a burrow and provisions the first cells entirely alone.April to May.
2. 2Worker broodThe first brood emerges as small females who remain and forage for their mother rather than dispersing. She stays below, laying and guarding.June.
3. 3Reproductive broodA later brood produces males and full-sized females. They mate, the workers and foundress die, and the mated females overwinter.August to September.

Where it lives and what it does

Habitat

Firm bare soil in warm positions — paths, banks, brownfield land, gardens, vineyards and coastal cliffs.

Distribution

Southern and central Europe, North Africa and western Asia, reaching southern England.

Behaviour

The social flexibility is what makes it scientifically important. In warm southern parts of its range it is reliably eusocial with a worker caste; further north and at altitude the same species is frequently solitary, because the season is too short for two broods. It is one of the clearest natural demonstrations that eusociality is a conditional strategy rather than a fixed trait.

Pollination role

An abundant generalist pollinator, significant in aggregate through sheer numbers and season length.

High in aggregate through abundance rather than per-visit efficiency.

What it forages on

A broad generalist on small open flowers — composites, umbellifers and brassicas.

Honey

Produces no honey

None. Even a social colony stores only what the current brood will eat, because it does not survive winter.

Relationship with people

How people interact with it

Unnoticed by almost everyone and heavily studied by entomologists. Its aggregations in garden paths are occasionally reported as an infestation and cause no harm whatsoever.

Conservation

Widespread and expanding northwards. Like all ground-nesting bees it depends on bare firm soil, which sealing removes.