By Thom Luloff, Master Gardener in Training

On a warm spring morning in Ontario, a familiar hum drifts through the air. Low, steady, and purposeful, it comes from a black-and-yellow visitor weaving between garden blossoms—the Eastern Bumblebee (Bombus impatiens). To most of us, it’s a sign of summer’s return, but beneath that fuzzy exterior lies a fascinating story of evolution, resilience, and quiet importance.

Bumblebees belong to the genus Bombus, a group that diverged from honeybee ancestors around 25 to 40 million years ago (Hines, 2008). Unlike honeybees, which thrive in massive colonies, bumblebees are social but live in smaller, more seasonal groups. The Eastern Bumblebee has evolved as a master of cool and temperate climates, thanks to its thick fuzz and the ability to generate heat by vibrating its flight muscles—a survival skill that lets it fly on chilly mornings when other pollinators remain grounded (Heinrich, 2004).

Every spring, the story begins anew with a solitary queen who has survived winter hibernation beneath leaf litter (leave the leaves!) or soil. Emerging hungry, she forages for nectar and pollen while searching for a suitable nest site—often an abandoned rodent burrow or a hollow beneath grasses. There, she lays her first clutch of eggs, which hatch into female workers. These workers soon take over foraging, allowing the queen to remain in the nest and focus on laying eggs (Colla et al., 2011). As the colony grows through summer, new males and future queens are produced. Mating occurs in late summer and early fall, after which the old colony dies, leaving only the fertilized young queens to overwinter and begin the cycle again the following year.

Eastern Bumblebees are generalist foragers, meaning they visit a wide range of flowers. They sip nectar for energy and collect pollen to feed their larvae. Unlike honeybees, which rely heavily on certain crops, Eastern Bumblebees are flexible, visiting everything from clovers and goldenrods to tomatoes and blueberries (Goulson, 2010). Their unique ability to perform “buzz pollination”—vibrating flowers to release hidden pollen—makes them essential for crops like tomatoes, peppers, and cranberries, which depend on this technique.

In the grand web of life, Eastern Bumblebees are lynchpins. By transferring pollen as they forage, they ensure the reproduction of wildflowers and food crops alike. This not only feeds people but also supports wildlife, since countless birds and mammals depend on the seeds and fruits that bumblebees help create. In forests, meadows, and city gardens, their work sustains plant communities that form the backbone of biodiversity.

Despite their adaptability, Eastern Bumblebees face mounting challenges. Habitat loss from urbanization and intensive agriculture has reduced nesting and foraging opportunities. Pesticides—especially neonicotinoids—pose lethal and sublethal risks, impairing navigation and reproduction (Woodcock et al., 2017). Climate change adds another layer of stress, disrupting flowering times and exposing bees to extreme weather (Kerr et al., 2015). 

The Eastern Bumblebee may be small, but its impact is enormous. With every hum in your backyard or park, it carries the story of millions of years of evolution, a seasonal cycle of resilience, and a vital role in keeping our ecosystems alive. Protecting them means protecting the beauty and abundance of the natural world.

References

Colla, S. R., Richardson, L., & Williams, P. H. (2011). Guide to the Bumble Bees of North America. Princeton University Press.

Goulson, D. (2010). Bumblebees: Behaviour, Ecology, and Conservation. Oxford University Press.

Heinrich, B. (2004). Bumblebee Economics. Harvard University Press.

Hines, H. M. (2008). Historical biogeography, divergence times, and diversification patterns of bumblebees (Bombus). Systematic Biology, 57(1), 58–75. https://doi.org/10.1080/10635150801898912

Kerr, J. T., Pindar, A., Galpern, P., et al. (2015). Climate change impacts on bumblebees converge across continents. Science, 349(6244), 177–180. https://doi.org/10.1126/science.aaa7031

Woodcock, B. A., Bullock, J. M., Shore, R. F., et al. (2017). Country-specific effects of neonicotinoid pesticides on honey bees and wild bees. Science, 356(6345), 1393–1395. https://doi.org/10.1126/science.aaa1190