Giant Patagonian bumblebee

How to recognise it

Enormous and unmistakable: entirely covered in long, dense, bright orange-ginger hair with no banding whatsoever. Locally called moscardón, and often described by visitors as a flying mouse.

• Very large — queens over 40 mm, the biggest bumblebee anywhere.
• Uniformly bright orange-ginger with no bands or contrasting colours.
• Restricted to the Valdivian temperate rainforest and Patagonian forest of Chile and Argentina.
• Increasingly absent where introduced European bumblebees are established.

Body length 15–40 mm (typically 28 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

50–200 individuals

Colony lifespan

One season.

Winter

Mated new queens overwinter alone.

Castes

Queen, Workers, Males, New queens

Nesting

Burrows in the ground; Existing cavities and tubes

Nests in cavities at or below ground level in forest and forest edge, including in dead wood and among tree roots.

Carries pollen

Corbicula (pollen basket) on the hind leg

On the wing

September to April

Lifecycle

1. 1Spring emergenceQueens emerge in the southern spring as the temperate rainforest flora comes into flower.September to November.
2. 2Forest seasonColonies build through the southern summer on native forest flora.
3. 3ReproductionReproductives in late summer and autumn.

Where it lives and what it does

Habitat

Valdivian temperate rainforest, Nothofagus forest and forest edge in southern Chile and Argentina.

Distribution

Endemic to southern South America. Formerly abundant throughout; now largely absent from central and northern Chile and retreating southwards ahead of the introduced species.

Behaviour

A large-bodied forest bumblebee adapted to the cool wet conditions of the Valdivian rainforest, and an important pollinator of native flora including several plants with no alternative pollinator of comparable size.

Pollination role

A keystone pollinator of Chilean temperate rainforest, and irreplaceable for large-flowered native species that smaller introduced bees cannot service effectively.

Very high, and functionally irreplaceable for several native plants.

What it forages on

Native Valdivian forest flora, including ulmo, quillay, notro and several endemic genera.

Honey

Keeps only a few days of stores

A few days' worth in wax pots. It is a pollinator rather than a honey producer.

Relationship with people

How people interact with it

The sequence is well documented. Bombus ruderatus was introduced to Chile from Europe in 1982 for red clover, and Bombus terrestris from 1997 for glasshouse tomatoes. Both escaped and spread rapidly. Bombus dahlbomii declined in step, and the spread of the parasite Apicystis bombi carried by the introduced species is strongly implicated alongside direct competition.

Conservation

Listed as Endangered by the IUCN. It is among the most cited examples anywhere of the risks of moving commercially reared bees between continents, and its decline is the strongest single argument for restricting that trade.