Appreciate our common Eastern bumblebees, because our colonies are fewer and still at risk
If you see a bumblebee now, it is most likely a common Eastern bumblebee (Bombus impatiens). These fuzzy, gentle cuties are still plentiful, while many other bumblebees are gone until next summer. The workers and males of other bumblebee species have all died out; only their queens live on, overwintering in nests on or in the ground. Each queen will reappear in the spring or summer to start a colony anew.
But common Eastern bumblebees are still buzzing around our fall asters and goldenrods. The queens of common Eastern bumblebees first awoke in April when temperatures rose, and the worker bees will still toil away throughout October.
When the mated common Eastern bumblebee queens emerged in April, they fed on early blooming flowers, drinking nectar for energy. Then they found an abandoned burrow in which to build a nest 1 to 3 feet below the surface. The queen gathered fibers such as hair or grass to make a hollow ball into which she deposited nectar-moistened pollen. She laid eggs inside the ball. The queen sat on the eggs to keep them warm, and after about five days, the eggs hatched into larvae, also known as grubs. The queen collected pollen and nectar to feed the larvae, which grew until they were large enough to form a cocoon about two weeks later. (Nectar provides bees with carbohydrates and water. Pollen, which is about 80 percent protein, provides protein for bees and their larvae.)
After another 10 days, each bee emerged from its cocoon as an adult bee. The entire process from egg to adult took four or more weeks, depending on temperature. (Bumblebees, like butterflies, undergo a complete metamorphosis, but bumblebees undergo metamorphosis underground where people do not see the stages of development; consequently, we often do not think about bees as existing in any stage other than as an adult bee).
A few days after they emerge, the adult bees take over food-gathering duties from the queen. From then on, the queen’s only job is to lay eggs, while the other bees collect pollen and nectar and take care of the hive. Over the summer, more generations of bees hatch and the colony grows. By late summer, the colony begins to rear male bees and new queens who leave the nest. The males wait on flowers to mate with the new queens. By the end of the season, the old queen, the males and the worker bees have all died. Only the new queens survive. They each dig a small hole underground, where they hibernate until April and emerge to start new colonies.
Bumblebees bet everything on the survival of these queens. But many queens and early bee colonies do not survive. In fact, over the past hundred years, the number of bumblebee species in Massachusetts has declined to seven from 11. And three of those seven are in danger of disappearing from our state in the next decade. This is bad news, because losing a bee species can lead to the loss of a plant species that relies on that bee species for pollination. This can lead to the loss of birds that eat and shelter in that plant, which can lead to the loss of animals that prey on the birds, and so on up the food chain. Eventually, too many species will be gone and our ecosystems will not function.
Much is unknown about bumblebees and how to help them because they haven’t been well studied, but scientists do know some things about them. Climate change, habitat loss, pesticide use, pollution, the introduction of nonnative plants and animals, and the loss of native plants and animals all contribute to the decline of bumblebees.
There are some things we can do to help our native bumblebees, though.
Right now is a good time to create bee nesting sites by leaving gardens intact as much as possible. Wait until late May or June to clean up that garden. By then, the queens should have emerged from the grass or soil. (Your garden might look a little messy, but only to human eyes. Bees may view your mess as an attractive overwintering hotel.)
You can also help bumblebees by planting native plants that flower from spring to fall and leaving these areas as undisturbed as possible. Scientists have discovered that neighborhoods with more backyard gardens have higher bee diversity than neighborhoods with fewer backyard gardens. It makes sense that a neighborhood with a greater diversity of bee food would have a greater diversity of bees.
Learn more about bees:
- “A Review on Bees,” published by the University of Massachusetts, Amherst.
- “The Secret Lives of Wild Bees,” a video talk by Nick Dorian of the Tufts Pollinator Initiative
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Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.