Yellow-legged mining bee

How to recognise it

A medium brown-grey bee with pale hair bands across the abdomen and, as the name says, distinctly orange-yellow hair on the hind legs. Males are slimmer with a pale face.

• Orange-yellow pollen brushes on the hind legs, conspicuous on a foraging female.
• Pale abdominal hair bands on a grey-brown body.
• Two flight periods — March to May and again June to August — which almost no other Andrena has.
• Very large nesting aggregations in south-facing banks, paths and cliffs.

Body length 10–13 mm (typically 11 mm).

Biology

Social organisation

Solitary

Each female builds and provisions her own nest with no workers and no caste. Most of the world's bee species.

Nesting

Burrows in the ground

Digs burrows in firm bare or sparsely vegetated soil, strongly favouring south-facing banks, and nests in aggregations that can reach many thousands. The aggregations persist for years and are frequently the same sites generation after generation.

Carries pollen

Scopa — dense hairs on the hind leg

On the wing

March to September

Lifecycle

1. 1Spring generationAdults emerge in March, mate and provision cells through April and May.March to May.
2. 2Summer generationThe offspring of the spring generation emerge in June and produce a second brood — bivoltine behaviour that is rare in the genus.June to August.
3. 3OverwinteringThe second generation's offspring overwinter underground and emerge the following spring.Roughly seven months.

Where it lives and what it does

Habitat

South-facing banks, coastal cliffs, quarries, brownfield land, gardens, footpaths and chalk grassland.

Distribution

Across Europe, North Africa and into Asia. Expanding northwards in Britain over recent decades.

Behaviour

Fast, low and busy, and unusually easy to observe because the aggregations are dense and the bees ignore people entirely. Its two generations mean it exploits both the spring blossom and the summer composites, which is a broader window than most mining bees manage.

Pollination role

A useful generalist pollinator across both halves of the season, and abundant enough to matter in aggregate. It works oilseed rape heavily in spring and composites and umbellifers in summer.

High through abundance and season length rather than per-visit efficiency.

What it forages on

A broad generalist — brassicas and blossom in spring, composites and umbellifers in summer.

Honey

Produces no honey

None. One pollen loaf per cell, no colony, no winter store.

Relationship with people

How people interact with it

Encountered mostly as a supposed infestation when an aggregation appears in a lawn or a bank. It causes no damage and the bees are gone within weeks, and an aggregation is one of the best things a garden can host for anyone wanting to watch wild bees.

Management

Nothing needs doing. Do not water, level or treat the mounds; mowing normally is harmless.

Conservation

Widespread and increasing. Like all ground-nesting bees it is squeezed by soil sealing — paving, artificial grass and landscape fabric all remove nesting habitat.