Small scissor bees
A genus rather than a single species — Around 60 species worldwide, mostly northern hemisphere, and many of them tight floral specialists. General statements below are statements about the group.
Tiny, slender, cylindrical mason-bee relatives that nest in the narrowest cavities of any bee — beetle holes barely two millimetres across — and several of which provision their cells with pollen from a single plant genus. The harebell carpenter bee uses campanula pollen and nothing else, and males sleep inside the closed bells.
Can it sting?
Far too small to sting a person meaningfully. Males cannot sting at all, and are frequently found asleep inside closed campanula flowers.
How to recognise it
Very small and distinctly elongated, black and sparsely haired, with a cylindrical body quite unlike the stocky build of most mason bees. Females carry pollen on the underside of the abdomen.
- Tiny and narrowly cylindrical — the shape is diagnostic.
- Pollen carried on the underside of the abdomen, not on the legs.
- Entering very narrow holes in dead wood, often 2-4 mm.
- Several species found only on one plant genus — campanula, or buttercups.
Body length 5–10 mm (typically 7 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; Hollow stems and plant cavities
Uses very narrow existing cavities — old beetle borings in dead wood, fine hollow stems, and the smallest tubes in a bee hotel at 2-4 mm, a size most commercial hotels omit entirely. Cells are separated with chewed plant material and mud.
- Carries pollen
- Scopa on the underside of the abdomen
- On the wing
- May to August
Lifecycle
- Emergence timed to the host plantAdults emerge when their host plant flowers — harebell carpenter bees with campanulas in June, others with buttercups earlier.May to August.
- ProvisioningFemales collect pollen from the host genus exclusively and provision cells in narrow tunnels.Several weeks.
- OverwinteringThe larva develops and overwinters in the cell.Roughly ten months.
Where it lives and what it does
- Habitat
- Gardens, woodland edge, hedgerows, old fence posts and brownfield land with dead wood and the host plants nearby.
- Distribution
- Across Europe, Asia and North America.
- Behaviour
- Quick and easily overlooked. The specialism is the interesting part: Chelostoma campanularum and C. rapunculi provision cells only with campanula pollen, so their presence depends entirely on bellflowers within a very short flight of a suitable cavity. Males sleeping in closed bellflowers is a reliable way to find them.
- 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.
- What it forages on
- Tight specialists — campanulas for two of the commonest species, buttercups and related genera for others.
Honey
Produces no honey
None. One small pollen loaf per cell.
Relationship with people
- How people interact with it
- Almost never noticed, and an argument for bee hotels with much finer tubes than the standard 8 mm. Anyone growing campanulas in a garden with dead wood nearby probably has them.
- Conservation
- Localised and dependent on the coincidence of host plant and fine cavities within a short distance. Removing dead wood or the host plant removes the bee.
Sources
- Field Guide to the Bees of Great Britain and Ireland — Bloomsbury (2015) · Field guide
- The Bees of the World — Johns Hopkins University Press (2007) · Textbook
How sources are selected and weighted is set out in the sources and evidence policy.
Guides covering this bee
- Why flowering seasons matterBees and flowers have to be in the same place at the same time. That synchrony is being pulled apart by warming, and for specialist bees with narrow windows it is a serious problem.
- How to actually help beesRanked by how much difference it makes, from the things that genuinely work down to the things that are mostly gestures. The first item on the list is not planting flowers.
- How to make a garden genuinely useful to beesMost bee-friendly advice covers flowers in June, which is the one thing bees are least short of. The gaps are at the ends of the year — and half the problem is not flowers at all.
- The best flowers for beesHerbaceous flowers rather than trees and shrubs, chosen for output and length of season. Most of them are things you can grow in a border or a container.
- Bee plants for a small gardenA small garden cannot do everything, so it should do the things large gardens usually skip: the winter and early spring gaps, and nesting habitat. Both take almost no space.
- Bee plants for a balconyBees will find a balcony several floors up, and containers can be genuinely productive. The constraints are watering, wind and depth, and the plants that handle all three are mostly Mediterranean herbs.
Tools for supporting this bee
- Plant recommendation tool
Which plant fills this specific gap?
- Bee-friendly garden planner
What should I plant in the space I actually have?
- Flowering calendar
What should I plant so that something is always in flower for bees?