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Insects and other arthropods

Bumble bees

English
Bombus
Common Eastern bumble bee (Bombus impatiens)
Photo: Ville de Montréal/Espace pour la vie/André Sarrazin
Common Eastern bumble bee
  • Common Eastern bumble bee
  • Bombus ternarius
  • A tricolored bumble bee with pollen accumulated on its hind legs
  • Common Eastern bumble bee
  • Hive of common Eastern bumble bee
  • Queen tricolor bumble bee

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Description

Bumble bees are large, sturdy, fuzzy bees, about 2 cm long. Their bodies are often black and yellow, sometimes with orange, red, or white markings. There are more than 250 bumble bee species worldwide, including about 50 in North America.

In Quebec, more than 20 bumble bee species are found, including the common eastern bumble bee (Bombus impatiens) and the rusty-patched bumble bee (Bombus affinis).

Pollination

Bumble bees are essential pollinators that help maintain plant diversity. In Quebec, they pollinate many cultivated crops, including tomatoes, raspberries, strawberries, and blueberries.

Bumble bees are such effective pollinators thanks to a few key physical adaptations:

  • Setae, the tiny “hairs” that cover an insect’s body, which catch pollen as the bee moves from flower to flower.
  • Pollen combs, structures on the hind legs used to brush pollen off the body.
  • Pollen baskets (corbiculae), also on the hind legs, which pack and carry pollen back to the nest.

Bumble bees also use a special technique called buzz pollination to release pollen from flowers where it is harder to access, such as tomatoes and eggplants. The bee grips the flower and rapidly vibrates its flight muscles, shaking pollen loose.

Each bumble bee refines this technique over time. Older workers develop a wider range of vibrations, allowing them to pollinate more kinds of flowers.

Geographic range and habitat

Bumble bees’ large size and abundant setae help them thrive in colder environments across North America, Europe, and Asia. A smaller number of species also occur in tropical regions of South America and Southeast Asia.

Bumble bees are found in forests, mountain regions, peatlands, fields, and other places where nectar-producing plants bloom.

Life cycle

Bumble bees are social bees that live in organized colonies made up of three castes: a queen, workers, and males.

In the few tropical species, a colony can survive for several years. In seasonal climates, however, bumble bees follow an annual cycle and form new colonies each year.

Only young, mated queens survive the winter, sheltered underground. The rest of the colony dies as cold weather sets in.

Queens emerge early in spring and search for a nesting site, usually an existing cavity.

In the chosen nest, the queen builds two cells from wax and pollen. She lays about ten eggs in one cell on a supply of pollen and nectar. She then fills the other cell with nectar, using it as a pantry while she tends her eggs.

She seals the cells with wax and settles over the brood to incubate it. After about four days, the larvae hatch and feed within the cell. At this stage, the queen alternates between caring for the larvae and collecting pollen.

After about two weeks, the larvae spin a silk cocoon and pupate. About two weeks later, adult workers emerge. These sterile females care for the next generations while the queen continues laying eggs and building new cells.

Bumble bees do make honey to feed the colony, but far less than honey bees do. They store it only to meet the colony’s short-term needs.

Once the colony reaches a certain size, the queen lays unfertilized eggs that develop into males and fertile females. As adults, they leave the nest to find mates and reproduce.

Defence

The abdomen of worker bees and queens ends with a stinger, used only for defence. Males do not have one. Unlike some other bees, bumble bees can sting more than once because their stinger is smooth and withdraws easily. Away from the nest, they are generally very calm.

Bumble bees’ contrasting colours act as a warning to potential predators.

French name
Bourdons
Scientific name
Bombus
English name
Bumble bees
Class
Insecta
Order
Hymenoptera
Family
Apidae