HoneyHQ

Plasterer bees

ColletesSolitaryProduces no honey

A genus rather than a single species — Around 500 species worldwide, with about nine in Britain — including the ivy bee, which was not described as a species until 1993. General statements below are statements about the group.

Solitary ground-nesting bees that line their cells with a self-produced plastic. A female Colletes paints the walls of each cell with a secretion applied by her short forked tongue, which polymerises into a transparent, waterproof, cellophane-like membrane — a genuine biological polyester, and one of the most remarkable materials any insect makes. It waterproofs the cell against the damp sandy ground these bees prefer.

Can it sting?

Females can sting and effectively never do. There is nothing to defend, and the aggregations — which can run to many thousands of nests in a bank beside a footpath — are entirely safe to walk past. Males, which swarm conspicuously over emergence sites, cannot sting.

How to recognise it

Medium-sized bees with a distinctly heart-shaped face, a dense band of pale hair across the thorax and sharply defined pale bands on the abdomen. The short, broad, forked tongue is the family's defining anatomical feature and is unusual among bees.

  • Crisp, evenly spaced pale hair bands on the abdomen, sharper than in most similar bees.
  • A short forked tongue rather than the long pointed tongue of most bees.
  • Large nesting aggregations in bare sandy or light soil, often in banks and paths.
  • Cells lined with a shiny transparent membrane, visible if a nest is ever excavated.

Body length 7–15 mm (typically 11 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 light, well-drained, sun-exposed soil, very often in dense aggregations of thousands of separate nests in one bank. Each cell is lined with the polyester membrane before it is provisioned, and the provision is a semi-liquid pollen-and-nectar mixture rather than the firm loaf most solitary bees leave — the waterproof lining is what makes storing a liquid provision underground possible at all.

Carries pollen
Scopa — dense hairs on the hind leg
On the wing
April to October

The genus as a whole spans the season while individual species fly for only a few weeks.

Lifecycle

  1. EmergenceTiming varies by species and tracks the host plants closely — spring species emerge in April, the ivy bee not until September.
  2. NestingThe female excavates, lines each cell with the secretion, provisions it with a semi-liquid pollen mixture and lays a single egg on the surface.Four to eight weeks.
  3. OverwinteringThe larva consumes the liquid provision and overwinters in the sealed waterproof cell, emerging the following year.Roughly ten to eleven months.

Where it lives and what it does

Habitat
Coastal dunes and cliffs, heathland, sandy banks, quarries, brownfield sites, footpaths, churchyards and lawns.
Distribution
Worldwide except Australia, with substantial diversity in Europe, North America and southern Africa.
Behaviour
Many species are specialists tied closely to one plant family, which makes their flight periods narrow and precisely timed. The mass emergences at a large aggregation are among the more dramatic wild bee spectacles available, and are routinely mistaken for a swarm.
Pollination role
Efficient pollinators, with the specialists particularly effective on their host plants. Their short tongues restrict them to open and shallow flowers, so they concentrate on composites, umbellifers, heathers, ivy and willow rather than on deep-tubed plants.

High on the shallow and open flowers they are built for, and negligible on deep-tubed ones.

What it forages on
A mix of generalists and tight specialists. Individual species are tied to willow, heather, ivy, composites or umbellifers, and the specialists disappear wherever their host plant does.

Honey

Produces no honey

None. A semi-liquid provision sized for one larva, in a sealed waterproof cell.

Relationship with people

How people interact with it
Encountered mostly as alarming-looking aggregations in lawns and banks, and mostly reported as a problem they are not. The polyester secretion has attracted genuine scientific interest as a naturally produced biodegradable polymer.
Management
Nothing needs doing about an aggregation. The bees are harmless, the ground is not damaged, and the same site will very likely be used again next year — which is worth valuing rather than removing.
Conservation
Several species are scarce and declining with the loss of bare sandy ground and of their specific host plants. Soil sealing removes nesting habitat that looks like waste ground to a human eye and is prime real estate to a 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.

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