Gardening for Bees

I can’t say exactly when I fell in love with bees. Perhaps it was the time I saw perfectly round, dime-sized holes cut into dozens of bright green leaves of the Clarkia plants I was carefully cultivating. It slowly dawned on me that the only possible explanation was that leaf-cutter bees had discovered an alternate use for my Clarkia leaves. I was familiar with leaf-cutter bees from PBS shows on the biodiversity of far-away tropical places. Could they really live here in San Francisco, too? Sure enough, they do. Or perhaps it was after I read “Bumble Bee Economics” by Bernd Heinrich, and learned that bumble bees can maintain a steady, high body temperature essential for their flight muscles to work over a very broad range of ambient temperatures from near freezing to well into the 90s. This is an incredible feat of biomechanical engineering for such a small creature. That’s one reason whyyou see bumblebees, and not honey bees, foraging for nectar or pollen on cold days. Or perhaps it was when Iread that more than 450 species of native solitary bees had been identified within Pinnacles National Monument just south of us in San Benito County. Talk about biodiversity! Or perhaps…

There are about 130 species of bees found in the Bay Area. Most are solitary bees, meaning a single female bee builds and provisions her own nest without the help of other bees. Others, like bumblebees, are semi-social. A single fertilized female bee starts a colony in spring that can grow to up to 250 bees by the summer’s end, when all the bees die except for recently fertilized females that overwinter in a sheltered hole in the ground. A less common lifestyle is exhibited by the introduced European honey bee, one that is fully social. It forms large colonies of thousands of bees that live together, provisioning and enlarging the swarm throughout the year.

Luckily for bee-lovers like me, it’s easy to create bee-friendly gardens. All you have to do is give them what they want – water, flowers, and nesting sites – and avoid what they don’t want – pesticides (it’s best for bees and other beneficial insects to avoid all use of pesticides). Native plants evolved with the local bee species and are the best choice for attracting them into your garden. Try selecting plants that flower at different times of the year to maximize the duration of flowering in your yard. I can’t recommend arroyo willow (Salix lasiolepis) too strongly. It’s one of the earliest flowering species in our area and draws bumblebees from far and wide to gather pollen in my garden. Once I introduce a new generation of bumblebees to my backyard with willow flowers, I keep them coming back with silver beach lupine (Lupinus chamissonis), coffeeberry (Rhamnus californica), ceanothus (Ceanothus thrysiflorus), California poppies (Eschscholzia californica), phacelia (Phacelia californica), meadowfoam (Linmanthes sp.) (I know, it’s not indigenous to San Francisco), and bee plant (Scrophularia cailfornica).

Other types of bees seem to prefer other plants. I see what I suspect is a medium-sized solitary bee that is inordinately fond of checkerbloom (Sidalcea malvaeflora). I frequently find several bees curled up, seemingly lounging, in its blossoms. I keep a small patch of sunny ground free of vegetation for these bees because I’ve noticed that they burrow small holes, about 1/4 inch in diameter, into the bare soil to excavate a home for their offspring. Other, even smaller, solitary bees seem to really enjoy my footsteps-of-spring (Sanicula arctopoides) before moving on to seaside daisy (Erigeron glaucus). I don’t yet know where these bees make their nests.

One final word on bee gardening: Be sure to spend a lot of time just watching. I’m sure you will be surprised by what you will discover about the not-so-secret life of bees. Also, you adventurous types should be sure to check out the bee condos for sale at www.beeworks.com. I have yet to try these in my yard; maybe next year.

Posted in Gardening with Natives.

Randy Zebell

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