Buff-tailed bumblebee

How to recognise it

A large, robust bumblebee with two yellow bands — one on the thorax, one on the abdomen — and a tail that is buff or dirty white in the queen and usually whiter in the worker. Queens are conspicuously large, up to 22 mm, and are among the first bumblebees seen in spring.

• Two yellow bands and a buff-coloured tail; workers often have a whiter tail with a faint buff line where it meets the black.
• Queens are very large and among the earliest bumblebees on the wing, sometimes in February.
• Short-tongued, so it is frequently seen robbing nectar through holes bitten in the base of deep flowers.
• Nests underground, often in an old rodent burrow, with a steady traffic of bees at a hole in a bank or under a shed.

Body length 11–22 mm (typically 16 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

150–600 individuals

Colony lifespan

One season. Everyone dies in autumn except newly mated queens.

Winter

Mated new queens overwinter alone, dug into loose soil or leaf litter, and found a nest entirely on their own in spring. In mild urban areas of southern Britain and northwest Europe some queens now skip hibernation and found winter colonies instead.

Castes

Queen, Workers, Males, New queens

Nesting

Existing cavities and tubes; Burrows in the ground

Nests underground, very often in an abandoned mouse or vole burrow, and will also use cavities under sheds, in compost heaps and in wall voids. The queen builds a small wax honeypot at the nest entrance and a clump of wax cells, and incubates her first brood by shivering — she is functionally warm-blooded while doing it.

Carries pollen

Corbicula (pollen basket) on the hind leg

On the wing

February to November

Increasingly year-round in mild urban areas of southern Britain and northwest Europe, where winter-active colonies have become established.

Lifecycle

1. 1Queen emergenceA mated queen emerges from hibernation in late winter or early spring, feeds heavily to rebuild her flight muscles, and searches for a nest site — the low zig-zagging flight over banks and hedge bottoms in March is a queen house-hunting.February to April.
2. 2Colony foundingShe lays and incubates the first brood alone, foraging between bouts of shivering to keep the eggs warm. This is the most precarious phase and most attempts fail.Four to five weeks.
3. 3Colony growthThe first workers take over foraging and the queen stays in the nest laying. The colony grows through spring and early summer.
4. 4Reproduction and collapseIn late summer the colony switches to producing males and new queens. They mate, the old queen and all workers die, and only the mated new queens survive to hibernate.

Where it lives and what it does

Habitat

Almost everywhere: gardens, farmland, woodland edge, grassland, urban parks and coastal land.

Distribution

Native across Europe, North Africa and western Asia. Introduced for glasshouse pollination and now established in Japan, Chile, Argentina, Tasmania and elsewhere, where it is invasive.

Behaviour

A short-tongued generalist and a habitual nectar robber. Faced with a deep flower it cannot reach into — comfrey, honeysuckle, some salvias — it bites a slit in the base of the corolla and takes the nectar without touching the anthers. Honey bees then use the holes it makes. It also performs buzz pollination, gripping a flower and vibrating its flight muscles to shake pollen out of poricidal anthers, which is the entire basis of its commercial value.

Pollination role

Enormously important, and complicated. It buzz-pollinates tomatoes, peppers, aubergines and blueberries, which honey bees cannot do — before commercial bumblebee rearing, glasshouse tomatoes were pollinated by hand with vibrating wands. Its nectar robbing means some of its visits do no pollination at all, and its introduction outside its native range has caused documented harm.

Very high on buzz-pollinated crops, and reduced on deep flowers it chooses to rob rather than enter.

What it forages on

A broad generalist with a short tongue, favouring accessible flowers and robbing the ones it cannot reach.

Honey

Keeps only a few days of stores

Makes a form of honey — ripened nectar stored in a small wax pot near the nest entrance — but only a few days' worth. An annual colony has no winter to survive as a group, so there is nothing to store for. Nobody harvests it and there would be nothing worth harvesting.

Relationship with people

How people interact with it

Reared commercially on an industrial scale and shipped worldwide for glasshouse pollination, which has made it both economically vital and ecologically damaging. Its escape from glasshouses in Japan, Chile and Tasmania has led to competition with native bumblebees, and in Chile its arrival is strongly implicated in the collapse of the giant native Bombus dahlbomii.

Management

Commercial colonies are sold in boxes for glasshouse use with a defined working life of several weeks. Where they are used outdoors or allowed to escape, they compete with local bees and can spread pathogens into wild populations.

Conservation

Not remotely threatened — it is one of the few bumblebees that has increased. The conservation concern runs the other way: as an introduced species it has caused documented harm to native bumblebees in South America and Japan, and as a commercially reared one it is a route for pathogen spillover into wild populations.