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Bombus terrestris (buff-tailed bumblebee) and lucorum (white-tailed bumblebee)

6 common species
Bombus terrestris/lucorum
Bombus lapidarius
Bombus pratorum
Bombus pascuorum
Bombus hortorum
Less common species
Quick ID guide
Cuckoo bumblebees
North American species
Bombus impatiens
N. American cuckoos
Is it a bumblebee?
Other bees1, 2
Looks like a bumblebee
Free e-book on how to recognise the 6 common bumblebees available now from the downloads page.

Differences between queens of Bombus terrestris and B. lucorum - Workers and males - Nests - Caste determination in Bombus terrestris - Pollen basket - Nectar robbing - Males patrol mating circuits

Bombus terrestris overview

This is our largest bumblebee, and usually the first to emerge. The thing to note on the queen is the dirty orange colour of the hairs at the end of the abdomen. Also when Bombus terrestris and B. lucorum can be seen together the yellow hairs of B. terrestris appear more orangey while those of B. lucorum are more lemon yellow. Workers have a white tail, and are almost indistinguishable from Bombus lucorum workers. Lengths, queen 20-22, worker 11-17, male 14-16. Bombus terrestris is one of the main species used in greenhouse pollination, and consequently can be found in many countries and areas where it is not native; Tasmania for example.

Queen Worker
Male
{Bombus terrestris}
Same as worker

Bombus lucorum overview

Slightly smaller than Bombus terrestris, and with a white tip to her abdomen. Lengths, queen 19-20, worker 11-17, male 14-16. Populations are believed to be declining.

Queen Worker Male
{Bombus lucorum}
Bombus lucorum male
Bombus terrestris/lucorum worker foraging

Differences between queens of Bombus terrestris and B. lucorum

The queens Bombus terrestris and B. lucorum are usually the first to emerge in the spring. B. terrestris queens are the largest bumblebees we have in the UK. It is fairly easy to differentiate between B. terrestris and B. lucorum queens -

  • the yellow thorax hairs of terrestris are more dull orangey while those of lucorum are more lemony
  • B. terrestris has a brownish orange tip to her abdomen while B. lucorum's is white - hence the common names.

Workers and males

The workers of both species look like smaller versions of the lucorum queen. See the worker on the left. They are almost impossible to tell apart without dissection. The size range can vary quite a lot, but usually the smaller workers are from the earliest laid eggs. Bombus lucorum workers range from 0.04 - 0.32 g and the queens from 0.46 - 0.70 g; B. terrestris workers range from 0.05 g - 0.40 g.

The males have a many more yellow hairs (see the photograph near the bottom of the page), and a distinctive yellow nose. Of course they do not usually emerge until about August.

terrestris/lucorm worker on water lily

Nests

Both of these species make their nests in the ground, usually in old mouse or vole nests, and in the U. K. preferably facing south to keep the nest warm, though B. terrestris tends to prefer shadier sites.

Generally the nests of B. terrestris have a deeper and longer tunnel that those of B. lucorum. Tunnels of 2 metres long have been recorded. A favourite nesting site of B. terrestris is under garden sheds. Successful nests can have as many as 350 workers.

In the early days of the nest it is estimated that a Bombus terrestris queen may have to visit as many as 6000 flowers per day in order to get enough nectar to maintain the heat needed to brood her eggs. And during every foraging trip the brood will cool down, so the trips should be short. This is why it is vital that the nest is located close to rewarding flowers.

The cuckoo species of B. lucorum is B. bohemicus, and the cuckoo species of B. terrestris is B. vestalis.

Caste determination in Bombus terrestris

The queen secretes a pheromone, which, if present within the first 5 days of larval life determines that the larva will develop into a worker. If the pheromone in absent, and if the larva receives sufficient food (more than a larva destined to be a worker) during her final instar she will develop into a queen. Consequently a queen larva is larger than a worker larva. It is believed that caste determination works in a similar way for other bumblebee species too.

Bombus terrestris pollen basket

Pollen basket

The photograph above left and left shows the pollen basket of a Bombus terrestris queen. This is the modified tibia of the hind leg. The inside leg is covered with hairs to rub pollen off the body. This is then passed to the pollen press, which is formed by a comb on the tibia, and the press or auricle on the metatarsus. The levering action of these two press the pollen, and it is pushed up onto the shiny, flat or convex tibia. The surrounding hairs are stiff and hold the pollen safely until the bee reaches the nest.

Nectar robbing

Both species have comparatively short tongues for bumblebees, so they tend to forage on flowers with short corollas and daisy-type flowers. However they

terrestris/lucorm worker on water lily
Bombus terrestris/lucorum nectar robbing

are accomplished nectar robbers (see left). When they find a flower where the nectar is too deep down the corolla for them to reach they bite a hole near the base of the corolla and push their tongue through and drink the nectar. This can often be seen on vetches. Other bumblebees will use the hole, and late in the year I have even seen honey bees and wasps use holes made by bumblebees.

One of the best examples of nectar robbing is to be seen in the Cruickshank Botanical Gardens of the University of Aberdeen. Between the back of the Zoology building and the benches is a strawberry tree (Arbutus unedo), it has white, bell-shaped flowers with nectaries just out of reach of B. terrestris and B. lucorum. By the end of summer almost all of the thousands of flowers will have a hole at the base, and this hole will be used by all short-tongued nectar gathering insects, especially wasps.

When B. terrestris and B. lucorum aren't robbing flowers without pollinating them they are very useful pollinators of fruit trees, raspberries and blueberries. They also favour any flower with nectar or pollen that is easy to get at.

Males patrol mating circuits

All bumblebee males patrol mating circuits laying down a pheromone to attract new queens. The pheromone is used to scent-mark prominent objects (tree trunks, rocks, posts, etc) on the circuit. The circuit is marked in the morning, and after rain. The scent of some species can be detected by some humans. Usually they patrol at species specific heights. Bombus terrestris and lucorum males patrol at tree-top height. However this depends on the habitat.

The Bombus lucorum male on the right was found dead in July. The tip of one of his antennae is missing, but apart from that and some disarray to his wings, he was intact.

 

Bombus lucorum male
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