Giant resin bee

How to recognise it

Very large for a solitary bee at up to 25 mm, with a dark reddish-brown thorax covered in dense hair, a black shining abdomen with sparse hair, and dark smoky wings. The overall impression is of something between a hornet and a carpenter bee.

• Very large — noticeably bigger than a honey bee and approaching a carpenter bee.
• Reddish-brown furry thorax against a shining black abdomen.
• Dark smoky wings.
• Seen entering existing cavities and bee hotel tubes and sealing them with resin rather than leaves or mud.

Body length 14–25 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

Existing cavities and tubes; Resin-lined cavities; Tunnels excavated in wood

Uses existing cavities — old carpenter bee tunnels, beetle borings, bamboo, and bee hotel tubes of 10-14 mm — and seals cells with plant resin mixed with mud and wood debris. It does not excavate its own tunnel, which is why it competes for holes rather than making them.

Carries pollen

Scopa on the underside of the abdomen

On the wing

June to September

Lifecycle

1. 1EmergenceAdults emerge in midsummer, later than most cavity nesters.June to August.
2. 2Nesting and cavity competitionFemales provision resin-sealed cells in existing tunnels. Both sexes have been recorded harassing and evicting native Xylocopa carpenter bees from occupied nests, sometimes with fatalities.
3. 3OverwinteringOffspring overwinter in the sealed cells and emerge the following summer.Roughly ten months.

Where it lives and what it does

Habitat

Woodland edge, gardens, orchards and urban areas with standing dead wood and cavity-rich structures.

Distribution

Native to China, Japan, Korea and Taiwan. First recorded in North Carolina in 1994 and now across much of the eastern United States; first recorded in France in 2008 and now widespread across southern and central Europe.

Behaviour

Fast, loud and conspicuous. Its floral preferences are narrow relative to its size — it favours Sophora, Styphnolobium and other Asian legumes plus a limited native range — which means its main ecological effect is competition for nest cavities rather than for forage.

Pollination role

A competent pollinator of the plants it uses, and a poor substitute for the native bees it displaces because its floral range is comparatively narrow.

Moderate, and complicated by cavity competition with native species.

What it forages on

Narrow relative to its size, favouring introduced Asian legumes such as Japanese pagoda tree alongside a limited range of local flora.

Honey

Produces no honey

None. Solitary, with one provision per cell.

Relationship with people

How people interact with it

A case study in accidental introduction through the timber and nursery trades, and a corrective to the assumption that any bee arriving in a landscape is a benefit. It is also frequently killed as a hornet, which is a separate misidentification problem.

Conservation

Not of conservation concern and a conservation problem. Monitoring across Europe and North America is ongoing, and the recorded evictions of native carpenter bees are the main cause for concern.