Create Space for California Bumblebees

Buzzing among lilacs or the tomatoes in our vegetable gardens, big, fuzzy bumblebees are a welcome sight. San Diego counts four species of bumblebee native to the county, among them one that bears the name of the Golden State: the California bumblebee. This large, hairy insect ranges from Central America through western North America. Leif Richardson, a conservation biologist who coordinates the California Bumble Bee Atlas project for the Xerces Society, says that the bee thrives in multiple habitats and can be found from sea level to the tops of many of California’s highest mountains. Bee experts debate whether the California bumblebee is subspecies of the golden northern bumblebee, yet many San Diego naturalists consider it distinct.

Able to forage at cooler temperatures than most other bees, native bumblebees are important pollinators for our local ecology. A number of agricultural plants, such as tomatoes, peppers, apples, and avocados, depend on bumblebee “buzz pollination,” a phenomenon in which a bee dislodges extra pollen by grabbing a portion of the flower in her jaws while vibrating her wing musculature.

Unlike most other native bees, California bumblebees are social. Their colonies have a queen and worker bees. Colonies die out in the fall, with new queens overwintering underground and starting new colonies in the spring of the following year.

If you’re interested in spotting a California bumblebee, Mission Trails Regional Park is something of a hot spot. I see bumblebees often at Torrey Pines State Natural Reserve throughout the year, although summer is when they are the most active.

Bumblebees are difficult to distinguish from one another, but a telltale characteristic of the California bumblebee is its black face.

Once the most common bumblebee in the Golden State, the numbers of California bumblebees have declined since the 1990s. Richardson says, “Bumblebees in general are challenged by a range of stressors, including habitat loss, pathogen spread from agriculture, and competition with invasive honeybees.”

As individuals, we can nonetheless help the California bumblebee and other pollinators. “We stress that planting of native plant species can make a big difference for native insects,” Richardson says. And he emphasizes the importance of reducing or eliminating pesticide use on pollinator plants. Finally, climate change is affecting the range and physiology of bumblebees: “I think people who want to help bees should be aware of this, and consider it one reason to address the causes of climate change.”

Do more to support native pollinators by leaving small, shallow plates of fresh water in your yard and read

In Touch: Bumblebees

By Paul Hormick

» cabumblebeeatlas.org