[Pollinator] SF Chronicle Article: Study reveals desires of bees, native and non Plant clusters draw more buzz than isolated flowers

Wed Mar 21 18:24:01 PDT 2007

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/03/21/HOG9CONHKP1.DTL

Study reveals desires of bees, native and non

Plant clusters draw more buzz than isolated flowers

Ron Sullivan, Joe Eaton

Wednesday, March 21, 2007

<http://www.sfgate.com/cgi-bin/object/article?f=/c/a/2007/03/21/HOG9CONHKP1.
DTL&o=0&type=printable> California poppies, which are early blooming native
flowe...

What should you plant to attract native bees? Prompted by e-mails from
readers of The Chronicle's recent articles on native bees, we looked at UC
Berkeley Professor Gordon Frankie's Urban Bee Gardens Web site and other
resources, and came up with some ideas. 

Frankie -- along with UC Davis Professor Emeritus Robbin Thorp; Barbara
Ertter, the curator for the University and Jepson Herbaria of UC Berkeley;
and UC Berkeley research assistant Mary Schindler -- conducted an intensive
two-year study of bees in the urban gardens of Berkeley and Albany. 

Their census covered UC's Oxford Tract, the Peralta Community Garden and
private gardens. The bee counters tracked which bee species -- nonnative
honeybees, native bumblebees, mason bees and leafcutters -- visited which
flower species, and analyzed the traffic. 

One surprise was the sheer diversity of native bees holding out in the East
Bay -- 74 species representing five families. They tended to be picky: Only
5 to 10 percent of the plant species had measurable bee activity. A quarter
of those were Northern California natives, the rest exotics. 

Not surprisingly, the scientists found that honeybees and native bees showed
different preferences. There's a lot of history behind plant-pollinator
relationships. Native bees and plants evolved together, some so tightly
linked that one bee species might visit only a single plant species. 

Also, cultivated plants have been bred for color, form and scent -- traits
less important to bees than nectar or pollen rewards. Such plants, writes
Judith Larner Lowry in her new book "The Landscaping Ideas of Jays," are "a
waste of a bee's time." 

Some plants, like the 'Julia Phelps' cultivar of the native shrub ceanothus,
drew both honeybees and natives. Other natives, including tansy-leaf
phacelia, marsh gumweed, nakedstem buckwheat, clarkia and lupine, were
patronized mostly by native bees -- as were a few nonnatives such as cosmos
and coneflower. A few plant families, including composites and salvias, seem
especially attractive to native bees. The Urban Bee Gardens site has an
extensive list. 

They may be slumming, but native bees also go for some weed species:
birdsfoot trefoil, bristly ox-tongue, wild mustard. Frankie recommends
tolerating these plants through their flowering cycle, then yanking them out
before they set seed. 

How you plant seems at least as important as what you plant. Clusters of
attractive species in the gardens Frankie surveyed were bee magnets;
isolated plants had much less traffic. Lowry suggests patches at least 16
feet in diameter. And early fliers like the metallic-green osmia bees
appreciate early bloomers, such as California poppies. The long-horned
melissodes bee visits sunflowers, cosmos and gaillardia in summer and early
fall. 

Apart from the social bumblebees, native bees are solitary, nesting either
in cavities in deadwood or tunnels in the soil. Two-thirds of our native
species are ground tunnelers. Lowry's advice: Avoid landscape cloth and
leave some areas free of bark mulch to allow these bees access to the soil.
For the deadwood nesters, tolerating dead limbs in at least one corner of
the garden provides habitat. 

Will a native-bee garden also lure native butterflies? That depends. 

Butterflies are limited not by nectar sources but by the host plants on
which their caterpillars feed. While some species insist on native plants,
others have made the switch to exotics. The showy anise swallowtail now
depends largely on sweet fennel, and the fiery skipper has become a lawn
specialist. 

Arthur Shapiro of UC Davis was surprised to find red admiral caterpillars on
baby's tears, which are no kin to their traditional fare of stinging nettles
but must have tasted right. One butterfly, the gulf fritillary, followed
plantings of passion vine from its southeastern homeland into Northern
California. 

Shapiro reported that 29 of 32 butterflies known to breed in Davis fed on
exotic plants; 13 had no known native host plants. But this pattern may not
be universal. The most recent information we could find for San Francisco is
an article written by Harriet Reinhard about 1989, with a tally of 36
butterfly species, two-thirds of them dependent on native plants. 

Apart from natural hot spots like Glen Canyon Park, Twin Peaks (home to the
endangered mission blue) and Mount Davidson, Reinhard noted responses to
native plantings. Pipevine swallowtails, confined to a small patch near Lake
Merced, showed up on their host plant across town in the Strybing Arboretum.

So why not plant a native pipevine for this spectacular iridescent
black-and-blue butterfly, along with poppies, sunflowers and salvias for the
native bees? 

It's a win-win proposition: "Good habitat for native bees, butterflies,
beetles, flies and other pollinators is also good garden design," Lowry
said. For inspiration, you can check out the Oxford Tract bee gardens during
the East Bay's free Bringing Back the Natives tour on May 6. A select tour
on May 5 also includes two showplace butterfly gardens. 

  _____  

Resources 

-- Gordon Frankie's Urban Bee Gardens site:
nature.berkeley.edu/urbanbeegardens 

-- Art Shapiro's Butterfly site: butterfly.ucdavis.edu 

-- Bringing Back the Natives tour: 10 a.m.-5 p.m. May 6.
www.bringingbackthenatives.net/2007gardens/Berkeley/Bee; Kathy Kramer, (510)
236-9558. The bee and butterfly garden tour is Select Tour No. 4. 

Joe Eaton and Ron Sullivan are freelance nature and garden writers in
Berkeley. E-mail them at home at sfchronicle.com. 

http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/03/21/HOG9CONHKP1.DTL

This article appeared on page G - 8 of the San Francisco Chronicle

Jennifer Tsang
Coevolution Institute <http://coevolution.org> 
423 Washington St. 5th Fl.
San Francisco, CA 94111-2339
T: 415.362.1137

F: 415.362.3070

www.nappc.org

www.pollinator.org

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