Carpenter bees

How to recognise it

Large and robust, 12-30 mm, with a characteristically shiny and largely hairless abdomen — the single feature that separates them from bumblebees at a glance. The thorax is furry, the abdomen is not. Many are black; some are metallic blue, green or violet.

• Shiny, bare abdomen. A bumblebee of the same size is furry all over.
• Very large — often the largest bee in the area — with a loud, deep buzz.
• Frequently seen hovering territorially around wooden structures, or entering a perfectly round 12-15 mm hole in a beam or fence post.
• Males of many species have a pale or yellow face patch and cannot sting at all.

Body length 12–30 mm (typically 20 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

Bores a round entrance hole into dead or weathered wood and then turns to tunnel along the grain, partitioning cells with chewed wood pulp. They prefer soft, unpainted, weathered timber and dead standing wood, and they do not eat the wood — it is excavated and discarded. Some species show simple social nesting in which a daughter remains and shares the nest, which sits at the very beginning of the road to sociality.

Carries pollen

Scopa — dense hairs on the hind leg

On the wing

March to October

Lifecycle

1. 1Overwintering adultsUnusually among solitary bees, carpenter bees generally overwinter as adults inside their tunnels, which is why they appear so early and so suddenly in spring.Several months.
2. 2NestingFemales excavate or reuse a tunnel, provision cells in a line and seal them. Tunnels are often reused and extended over successive years, which is how a beam accumulates real damage over decades.Spring into summer.
3. 3New adultsOffspring emerge in late summer, feed, and return to a tunnel to overwinter.

Where it lives and what it does

Habitat

Warm regions with dead wood: woodland edge, orchards, gardens, old buildings, fence posts and vineyard stakes.

Distribution

Worldwide in warm temperate and tropical regions. Xylocopa violacea has expanded its European range noticeably northwards in recent decades and now reaches southern Britain.

Behaviour

Notable as habitual nectar robbers: rather than entering a long tubular flower from the front, a carpenter bee slits the base of the corolla with her mandibles and takes the nectar directly, pollinating nothing. Other bees, including honey bees, then use the hole she made. It is one of the clearest cases in nature of a flower visitor that is not a pollinator, and a useful corrective to the assumption that any bee on a flower is doing the plant a favour. On flowers they can enter legitimately, they are effective, and several species buzz-pollinate.

Pollination role

Genuinely mixed. Important and effective pollinators of large open flowers and of several tropical crops including passionfruit, and capable buzz-pollinators. On deep tubular flowers they frequently rob rather than pollinate. The honest summary is that they matter, and not uniformly.

Highly effective on some flowers and actively unhelpful on others, because of nectar robbing. A single rating for the genus would conceal the whole point.

Honey

Produces no honey

Relationship with people

How people interact with it

Mostly a nuisance reputation they only partly deserve. They will tunnel into fascias, decking, fence rails and garden furniture, and over many years of reuse the damage to a specific beam can be real. They are also large, loud and given to flying at people, which does the rest. Painted or hardwood timber is largely avoided; leaving dead wood elsewhere in a garden gives them somewhere better to go.

Conservation

Not generally threatened, and some species are expanding their range as the climate warms. Dependent on standing dead wood, which tidy management removes.