Blunthorn bees

How to recognise it

Medium-sized, dark, moderately hairy bees with pale abdominal hair bands, superficially resembling mining bees. Females have dense pollen brushes on the hind legs. The blunt antennal tips give the group its English name.

• Superficially like a mining bee — dark with pale bands and leg pollen brushes.
• Found on one plant genus and effectively nowhere else, depending on species.
• Flies in high summer rather than spring, unlike most Andrena.
• Reliable identification generally needs a specimen.

Body length 8–14 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 bare or sparsely vegetated ground, generally close to a stand of the host plant. Because both nest site and forage must be within a short flight, the bee needs the two together rather than merely in the same landscape.

Carries pollen

Scopa — dense hairs on the hind leg

On the wing

June to September

Lifecycle

1. 1Emergence timed to the hostAdults emerge when the host plant flowers, which for most species means midsummer rather than spring.June to August.
2. 2ProvisioningFemales collect pollen from the host genus exclusively and provision cells alone.Four to six weeks.
3. 3OverwinteringThe larva develops on the provision and overwinters underground.Roughly ten months.

Where it lives and what it does

Habitat

Unimproved grassland, heathland, chalk downland, brownfield land and coastal grassland with the host plants abundant.

Distribution

Europe, Asia and Africa, with a smaller representation in North America.

Behaviour

Strictly oligolectic in most species: Melitta haemorrhoidalis on bellflowers, M. tricincta on red bartsia, M. leporina on legumes, M. dimidiata on sainfoin. A population exists as a satellite of a plant stand and disappears entirely if that stand goes.

Pollination role

Effective pollinators of their host genera, several of which are visited by comparatively few other insects.

High on the host plant and negligible elsewhere — the definition of an obligate specialist.

What it forages on

Tight specialists, each species on a single plant genus — bellflowers, red bartsia, legumes or sainfoin depending on the species.

Honey

Produces no honey

None. One pollen loaf per cell, no colony.

Relationship with people

How people interact with it

Almost unknown outside entomology, and scientifically important out of proportion to their profile — the Melittidae sit near the base of the bee family tree and are central to reconstructing what early bees were like.

Conservation

Several species are scarce and declining with their host plants. As with all specialists, losing the plant loses the bee, and the requirement for bare ground nearby makes them more demanding still.