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Ruderal bumblebee

Bombus ruderatusEusocial, colony dies each autumnKeeps only a few days of stores

Britain's largest bumblebee and one of its scarcest, a long-tongued legume specialist that declined severely through the twentieth century. It was also shipped to New Zealand and Chile in the nineteenth and twentieth centuries to pollinate red clover, and in Chile it became one of the introduced species implicated in the collapse of the native giant bumblebee.

Can it sting?

Can sting and effectively never does.

How to recognise it

Very large, with three yellow bands and a white tail in the banded form — closely resembling the garden bumblebee but bigger and with a shorter face. An entirely black form also occurs and is not uncommon.

  • Very large — the biggest British bumblebee.
  • Three yellow bands and a white tail, or entirely black in the melanic form.
  • Shorter face than the garden bumblebee, which it otherwise closely resembles.
  • Unimproved grassland, fen and old meadow rather than gardens.

Body length 14–22 mm (typically 18 mm).

Biology

Social organisation

Eusocial, colony dies each autumn

A true colony with a queen and workers, but only for one season: everyone dies in autumn except mated new queens, who overwinter alone. Bumblebees.

Colony size at peak
50–180 individuals
Colony lifespan
One season.
Winter
Mated new queens overwinter alone.
Castes
Queen, Workers, Males, New queens
Nesting
Burrows in the ground

Nests underground, usually in old rodent burrows in unimproved grassland and fen edge.

Carries pollen
Corbicula (pollen basket) on the hind leg
On the wing
April to September

Lifecycle

  1. EmergenceQueens emerge in April and May.April to May.
  2. Colony seasonBuilds on deep-corolla legumes through summer.
  3. ReproductionReproductives from late summer.

Where it lives and what it does

Habitat
Unimproved grassland, fen, damp meadow, ditch banks and old field systems.
Distribution
Across Europe. In Britain, a scarce and localised species concentrated in East Anglia, the fens and parts of the south. Introduced and established in New Zealand and Chile.
Behaviour
A long-tongued specialist on deep-corolla legumes, and its decline in Britain follows the same course as the other long-tongued species — red clover left the rotation and the bees went with it. Its introduction history makes it a double lesson: a species declining at home and causing problems abroad.
Pollination role
An effective pollinator of red clover and other deep legumes, valuable enough historically that it was shipped across the world for the purpose.

Very high on deep-corolla legumes, which few other bees can pollinate properly.

What it forages on
Deep-corolla legumes above all, plus comfrey, foxglove and toadflax.

Honey

Keeps only a few days of stores

A few days' worth in wax pots.

Relationship with people

How people interact with it
Exported deliberately to New Zealand from 1885 and later to Chile, in one of the earliest deliberate pollinator introductions anywhere. In Chile it preceded Bombus terrestris and is implicated alongside it in the decline of Bombus dahlbomii.
Conservation
Scarce and declining in Britain and across much of western Europe, with the loss of legume-rich grassland the principal cause. Simultaneously an introduced problem species in South America — a combination worth stating plainly.

Sources

  • Bumblebees: Behaviour, Ecology, and Conservation — Oxford University Press (2010) · Monograph
  • Field Guide to the Bees of Great Britain and Ireland — Bloomsbury (2015) · Field guide

How sources are selected and weighted is set out in the sources and evidence policy.

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