Large scabious mining bee

How to recognise it

A large mining bee, black with a red-marked abdomen in many females and conspicuously pale hair bands. Foraging females are unmistakable at close range because scabious pollen is a distinctive pale purple-grey, and a loaded bee appears to be carrying lilac.

• Large for a mining bee, at 13-16 mm.
• Carrying pale lilac-grey pollen — scabious pollen is a distinctive colour and effectively diagnostic.
• Found on field scabious and small scabious, and essentially nowhere else.
• Flies June to August, on dry calcareous grassland.

Body length 13–16 mm (typically 14 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 on dry calcareous soil 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 August

Lifecycle

1. 1Emergence timed to the hostAdults emerge in June, synchronised with scabious flowering rather than with the calendar.June to July.
2. 2ProvisioningFemales collect scabious pollen exclusively, and a single cell requires many visits.Four to six weeks.
3. 3OverwinteringThe larva develops on its scabious pollen provision and overwinters underground, emerging the following summer.Roughly ten months.

Where it lives and what it does

Habitat

Unimproved dry calcareous grassland, chalk downland, road verges and railway banks with abundant field scabious.

Distribution

Across Europe. In Britain, scattered and declining, concentrated on southern chalk and limestone.

Behaviour

A strict oligolege. A female will not provision cells with anything but scabious pollen, so a population exists as a satellite of a plant stand and disappears entirely if that stand goes. It also supports its own cleptoparasite, Nomada armata, which is rarer still.

Pollination role

An effective pollinator of field and small scabious, which are themselves major late-summer nectar plants for a wide range of other insects.

High on its host plants and zero elsewhere — the definition of an obligate specialist.

What it forages on

Field scabious and small scabious for pollen, obligately. It takes nectar more widely for its own fuel.

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 a standard indicator species in chalk grassland survey work. Its presence indicates a scabious population large enough to sustain a specialist, which in turn indicates grassland that has never been fertilised or reseeded.

Conservation

Declining with the loss of unimproved calcareous grassland. Because it needs both the plant in quantity and bare ground within flying distance, it is more demanding than the plant alone and is lost from sites where scabious persists in small numbers.