Everyone recognizes bumblebees: Yellow-furred, robust, and lumbering, their sonorous buzzing usually gets people’s attention. These tireless pollinators seem content to go about their work; only rarely—when they are molested or when their nests are threatened—will bumblebees become aggressive and sting.
It has been estimated that humans would not survive for a decade if bees were suddenly unavailable to pollinate our food crops. With the worldwide decline of honeybee populations, bumblebees are gaining recognition for the vital role that they, too, play in agriculture.
The bees, however, have always been around; their relatively newfound acclaim is a matter of human perspective.
Of the more than 250 species of bumblebees, most are found in the temperate zones of the northern hemisphere. They can range farther north than honeybees, having established colonies on Canada’s Ellesmere Island. A few species are found in South America, and bumblebees were introduced to New Zealand a century ago to pollinate clover.
Bumblebees are social insects: They form colonies with designated castes and cooperate in the rearing of young.
The Life Cycle of Bumblebees
- Each spring, a queen emerges from hibernation and seeks out a suitable nesting site. This can be an abandoned rodent burrow, a cavity beneath a stone, an attic, a clump of grass, or a similarly sheltered spot.
- The queen deposits eggs in specially-prepared wax cells within the nest. She then forages for pollen and nectar that she feeds to her first brood of larvae as they hatch.
- The larvae progress through several stages of development, called instars, before spinning silken cocoons and forming pupae.
- Pupae eventually develop into adult bees; the first emerging adults are worker females, which assume the task of foraging while the queen remains in the nest and continues to lay eggs.
- A bumblebee colony may eventually contain several hundred individuals.
- Later in the season, some of the eggs that are laid develop into male bees and new queens.
- New queens and males eventually leave the nest (or are actively driven out), where they forage on their own and eventually mate.
- Males die soon after mating; the newly-fertilized queens search for a suitable location for hibernation (known as diapause).
- Most bumblebee species don’t use the same nesting site for more than one season, and queens usually only live through one egg-laying season.
Bumblebee Facts
- Folklore has it that the laws of aerodynamics dictate that bumblebees shouldn’t be able to fly. Actually, sophisticated analysis shows that bumblebee wings encounter dynamic stall with each oscillation, thus providing more than enough lift to enable bumblebee flight.
- The buzzing produced by bumblebees does not come from their wings; rather, it is produced by the vibration of their flight muscles.
- Bumblebee stingers, unlike those of honeybees, are not barbed. Therefore, even though bumblebees aren’t likely to sting, one bee can sting multiple times.
- Bumblebees can sometimes be heard angrily vibrating within a blossom, as if trapped by its petals. Unlike other pollinators, bumblebees frequently use a technique called “buzz pollination”. Once on a flower, they can vibrate their flight muscles to loosen adherent pollen. Some plants, such as tomatoes and eggplants, are more efficiently pollinated in this fashion, making bumblebee culture an attractive option for growers of these crops.
- In some countries, bumblebees are endangered due to habitat destruction and pesticide use.
- Due to declining bumblebee numbers, the world’s first bumblebee sanctuary was established at Scotland’s Loch Leven National Nature Preserve in 2008.
Bumblebees are critical players in our ecosystem; without them, our landscape—and our future—would be bleak, indeed.
Stephen Allen Christensen - Dr. Steve Christensen's writing has appeared in magazines, professional journals, poetry anthologies, and children's books since 1976.
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