Violet carpenter bee

How to recognise it

Very large at up to 30 mm, entirely matt black with dense black hair, and wings that appear dark until the light catches them and turns them iridescent violet-blue. Males have a pale band on the antennae.

• Very large and entirely black, with violet-iridescent wings in sunlight.
• Loud, deep buzz — audible before the bee is visible.
• Seen entering round holes bored in dead wood, fence posts, beams and pergolas.
• Increasingly recorded in southern Britain, where it was a vagrant until recently.

Body length 20–30 mm (typically 25 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

Tunnels excavated in wood

Excavates tunnels in dead, dry, unpainted softwood — old fence posts, beams, dead branches, and structural timber. A female chews a round entrance hole and then a gallery running with the grain, provisioning a linear series of cells separated by chewed wood partitions. Tunnels are frequently reused and extended over years.

Carries pollen

Scopa — dense hairs on the hind leg

On the wing

March to October

Lifecycle

1. 1Overwintering as an adultUnusually, adults overwinter in tunnels and emerge in spring already mature, which is why very large black bees appear on warm days in early spring.Autumn to spring.
2. 2NestingFemales excavate or extend tunnels and provision cells through late spring and summer.Several weeks.
3. 3New generationThe new adults emerge in late summer, feed, and overwinter in tunnels to start again.

Where it lives and what it does

Habitat

Gardens, orchards, woodland edge, old buildings and anywhere with standing dead wood in warm sunny positions.

Distribution

Southern and central Europe, North Africa and western Asia. Expanding north — established in southern Britain since around 2007 after centuries as a rare vagrant.

Behaviour

Powerful, fast and loud. It is strong enough to force open flowers that exclude other bees, and it is also a habitual nectar robber, biting through the base of deep flowers it cannot enter. Males hold territories and investigate anything passing, including people, with no capacity to do anything about it.

Pollination role

An effective pollinator of large flowers that smaller bees handle poorly, and a nectar robber on deep ones. Its size makes it valuable for plants requiring force to open.

High on large flowers, and reduced where it robs rather than enters.

What it forages on

Large and deep flowers — legumes, comfrey, salvias, wisteria and Mediterranean scrub flora.

Honey

Produces no honey

None. Solitary, with one provision per cell.

Relationship with people

How people interact with it

Frequently reported as damaging timber, and the damage is real but modest — it uses wood that is already dead and dry, and structural harm is rare. Its northward expansion is one of the more visible insect range shifts in western Europe and is tracked largely through public sightings.

Management

If tunnels in structural timber are genuinely a problem, the answer is paint or varnish, which deters it. Untreated dead wood left deliberately elsewhere in a garden gives it somewhere better to go.

Conservation

Not threatened and expanding. Its constraint is standing dead wood, which tidy management removes.