Mining bees

How to recognise it

Variable, from 5 to 17 mm, and often strikingly furry. Several are unmistakable — the tawny mining bee is a bright foxy orange all over. Others are dark and unremarkable. Females typically carry pollen on dense hairs on the hind legs and often on the sides of the thorax as well, giving a dusty, loaded appearance rather than a neat pellet.

• Small conical mounds of fine excavated soil with a central hole, in short turf, bare paths or south-facing banks.
• Pollen carried loose and dusty on hairy hind legs, not compacted into a shiny pellet.
• Most species fly in a narrow window in spring and are gone by June.
• Many species have a velvety appearance and a distinct fringe of hair on the hind leg.

Body length 5–17 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

Each female digs her own vertical burrow with short side branches, provisions each cell with a pollen loaf, lays one egg on it and seals it. Where the ground is right, thousands of females may nest within a few square metres — an aggregation, not a colony. Every burrow is a separate household with its own front door, and no bee helps another.

Carries pollen

Scopa — dense hairs on the hind leg

On the wing

March to June

A minority of species fly in late summer and early autumn, most notably the ivy bee, Colletes hederae — a different genus but the same ground-nesting way of life.

Lifecycle

1. 1EmergenceAdults emerge from the previous year's cells in spring, males typically first. Mating occurs at the nest site, sometimes in conspicuous swarms of males over the ground.March to May for most species.
2. 2NestingThe female digs and provisions for four to eight weeks and then dies. She never sees her offspring.Four to eight weeks.
3. 3DevelopmentThe larva consumes its pollen loaf, develops through the summer and overwinters underground, usually as a pupa or a fully formed adult, ready to emerge in spring.Around ten months.

Where it lives and what it does

Habitat

Short turf, lawns, bare paths, south-facing banks, sandy soil, brownfield land, coastal dunes, woodland rides and gardens. Warm, bare, well-drained, sparsely vegetated ground is the requirement.

Distribution

Throughout the northern hemisphere, with very high species richness in temperate Europe, Asia and North America.

Behaviour

Much of what makes this genus important is dietary specialism. A large proportion of Andrena are oligolectic — collecting pollen from one plant family or even a single genus — which ties their flight period tightly to their host's flowering and makes them far more vulnerable than a generalist to the loss of one plant. The ashy mining bee works brassicas and umbellifers, several species work willow catkins almost exclusively, and one is tied to bryony.

Pollination role

Enormously important in spring, especially for orchard fruit, willows and early crops, at a point in the year when honey bee colonies are still small and reluctant to fly. Specialist species are often the most effective pollinators of their host plants by a wide margin, because their whole life history is built around that flower.

Honey

Produces no honey

Relationship with people

How people interact with it

Not managed and not harvestable. Mostly encountered as a misunderstanding: lawn mounds mistaken for ants or for a pest, and aggregations mistaken for a swarm. The correct response to both is to leave them alone.

Conservation

Several species are in serious decline, and the specialists are the ones falling fastest. The two requirements — bare warm ground and a specific flower in bloom at the right moment — are both routinely removed by tidy landscaping and intensive agriculture.