The Secretive Lives of Wild Bees

The nurturing hum of bees in the garden most often signals the presence of European honey bees, well-known for their pollination skills, hives and sweet, sweet honey. In recent years, Colony Collapse Disorder (CCD) has decimated honey bees across the country, and plenty has been written about their plight.

Far less frequently recognized are our native bees, which are not in danger of collapsing because, unlike their European cousins, the natives don’t congregate in hives. Nor do they produce honey.

Instead, they are solitary sorts that didn’t receive much scientific attention until CCD began wiping out honey bees, which prompted biologists to look for alternative bees. In a fortuitous turn of events, they discovered that wild bees pollinate up to 40% of California’s pollinator-dependent crops and contribute $2.4 billion a year to our state agriculture’s bottom line.

As for the home garden, we all know that more is better when it comes to bees and pollination. Setting up such enticements as pollen, nectar and places to nest to attract wild bees is an excellent way to keep our gardens healthy and our crops productive. Doing so also helps sustain honey bees, which settlers first brought to America in the early 1600s to make beeswax and honey.

A Few Facts

There are approximately 20,000 species of bees in the world. Some 4,000 species are native to the United States. A whopping 1,600 of those species are native to California and include about 25 species of bumblebees.

Have you ever noticed them? Step into a wildflower meadow on a sunny spring day and really start looking. On just one species of annual wildflower—Phacelia tanacetifolia—researchers from UC Berkeley have collected more than 60 different species of wild bees, according to Dr. Gordon W. Frankie, a UC Berkeley professor and co-author of California Bees & Blooms: A Guide for Gardeners and Naturalists.

Thankfully, our native bees don’t limit their appetites to native plants. For example, Frankie’s group also collected an astonishing 57 species of wild bees foraging on Provence lavender in a test garden at the university’s Urban Bee Lab.

Yet while California’s wild bees will feast on flowering plants from northern Mexico and the Mediterranean, Frankie told a recent audience at the Santa Barbara Botanic Garden that they’re not particularly interested in plants from Africa, Australia and New Zealand.

Providing Sustenance

In the garden, a number of flowering herbs and edibles are bee magnets. Annual herbs such as borage and cilantro serve sugary nectar and protein-filled pollen, as do perennial herbs such as catmint, germander, lavender, marjoram, oregano, rosemary, sage, teucrium and thyme.

But to sustain wild bees year-round, it’s important to know that most live only a few weeks, that there are seasons for the different species and that, altogether, they’re out and about for some 10½ months of the year, from mid-December through the end of October.

The trick, then, is to plant a year-round flower buffet. In the edible garden, Frankie suggests the following:

• Spring-blooming edibles: blackberries or raspberries, blueberries, fava beans and rosemary.
• Spring-blooming flowers: phacelia.
• Spring/Summer-blooming edibles: borage, oregano, strawberries, sunflowers and thyme.
• Spring/Summer-blooming flowers: California poppies and coyote mint (Monardella villosa).
• Summer/Fall edibles: basil, cilantro, cucumbers, globe artichokes, Jerusalem artichokes or sunchokes, melons including watermelons, tomatoes and zucchini.
• Summer/Fall-blooming flowers: blanketflower (Gaillardia x grandiflora) and sulfur cosmos (Cosmos sulphureus).

To that list, I would add planting arugula, broccoli and dinosaur kale (aka Tuscan or lacinato kale), then letting some of the plants set flowers. Also intersperse annual calendulas and zinnias with your vegetables. Then plant native shrubs around the perimeter, including the many beautiful sages and buckwheats (Eriogonum), along with manzanita (Arctostaphylos), which blooms while many flowering plants are resting in late winter and early spring.

Focus on sun-loving plants: Bees favor sun-lit flowers and typically emerge when temperatures reach 65°.

A Place to Nest

Honey bees swarm and gather in hives of up to 50,000 bees.

A few native bees—bumble bees and some sweat bees—live in small colonies of at most several hundred bees. But they don’t travel in tight packs or produce honey.

The majority of our wild bees nest alone in the ground, crevices, hollow-stemmed grasses and tree cavities. Females spend much of their time out of sight, building a successive line of about a dozen cells and depositing pollen and an egg in each. Males—which don’t sting—may stay out at night, sleeping within flowers or foliage.

While the prevailing advice during the drought has been to mulch, mulch, mulch, it’s necessary to leave some bare earth for native bees to drill their nests. Don’t worry—the nests are smaller than the diameter of a pencil, in most cases there’s only one bee per nest, wild bees don’t swarm and they’re not likely to sting unless threatened. Even if you’re actively looking, nests are incredibly difficult to find. You may see a multitude of wild bees in your garden, yet never find a nest.

Some vendors offer “bee condos.” Or you can simply drill small holes several inches deep into blocks of wood, or bundle together narrow, hollow sticks, and place them in an undisturbed spot in your garden. But earwigs or wasps may set up shop in the cavities.

It should go without saying to avoid using herbicides or pesticides in the garden, which can harm both the bees and the flowers they depend on.

Instead, planting a diverse group of nectar and pollen-rich plants should help you bypass any need to apply such controls. Bee-friendly plants support not only wild bees and honey bees, but many other beneficial insects, butterflies and birds. Bringing in all of these creatures will create a more robust ecosystem and improve your backyard bounty.