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Ruderal bumblebee

(Bombus ruderatus)

A Ruderal bumblebee male feeding on a bright pink flower.
A close-up of purple wildflowers on a farm verge.

Status
This is a scarce bumblebee. It is not found in Scotland and only occurs sporadically across the south of England. There are very few Welsh records.

Where to find
They tend to be found in flower-rich grasslands, especially those with a high density of red clover. Ruderal bumblebees appear to thrive in large river valleys and on agri-environmental pollen and nectar mixes.

A Ruderal bumblebee dark form feeding on a pale purple flower.

Tony Ayling

Active period

Ruderal bumblebee queens emerge from hibernation from April onwards.

Workers appear roughly 6 weeks after the nest is established, and new queens and males are produced towards the end of the three to four month nesting period.

This species has one nest per year but, due to queens emerging later in the spring and early summer, can still be seen up to the end of September.

Three identification illustrations of a Ruderal bumblebee queens, showing the light form queen, intermediate form queen, and dark form queen.

Description

All three castes (queen, worker and male) are similar, with two yellow bands on the thorax, one yellow band at the front of the abdomen, and a white tail. The yellow bands on the thorax are the same width. Some individuals appear very dark with little or no colour visible in the bands or even in the tail. This process is known as melanism (and individuals are referred to as melanic) because of the increased production of the dark pigment, melanin. Production of melanic individuals occurs in virtually all bumblebee species but seems to be particularly common in the Ruderal bumblebee.

Ruderal bumblebees nest mainly in old rodent burrows, and nests may have over 150 workers.

This species has a very long face and long tongue which enables it to feed on deep flowers like foxgloves.

Similar species and differences

The Heath bumblebee (Bombus jonellus) has a similar banding pattern and tail colour but has a shorter face, and individuals of all castes are generally much smaller and fluffier.

The Garden bumblebee (Bombus hortorum) also has a similar banding pattern and can be a similar size but has longer hair . Individuals of these two species can be very difficult to reliably separate.

Barbut’s cuckoo bumblebee (Bombus barbutellus) can appear similar but has a short face and a large box-shaped head. As with all cuckoo bumblebees, it also has darker wing membranes, hairy hind legs in both sexes (no pollen baskets), and sparser hair which allows the shiny exoskeleton to show through.