Home & Garden Columns

Wild Neighbors: Getting to Know Your Local Butterflies

By Joe Eaton
Tuesday May 29, 2007

I don’t usually devote this space to book reviews, but I’m making an exception for the latest in UC Press’s California Natural History Guides series: Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions, by Arthur M. Shapiro and Timothy D. Manolis. I know there are a bunch of good butterfly guidebooks out there already: Jeffrey Glassberg’s Butterflies through Binoculars: The West, Jim Brock and Kenn Kaufman’s Butterflies of North America, Paul Opler’s Field Guide to Western Butterflies. Well, make shelf room for the new one. 

Shapiro, who teaches at UC Davis (and is notorious for offering a pitcher of beer to whoever brings in the year’s first butterfly, a prize he tends to collect himself), is responsible for the text. Manolis, author and illustrator of the UC Press dragonfly guide, did the 31 color plates, showing all the variations by sex and season. There’s a hefty introduction to butterfly biology, a section on gardening for butterflies with a plant list, a glossary, a useful bibliography. My only real beef with the book is the absence of range maps. 

Every species gets a detailed account, covering life cycle, larval host plants, distribution, and separation from similar species. That last is especially helpful with the skippers, a confusing complex of small brown jobs that are the Empidonax flycatchers of the butterfly world. You’ll learn nifty words like diapause (a dormant period), multivoltine (having multiple adult emergences in a year), and sphragis (look it up; I’m not about to discuss the sex life of the clodius parnassian in a family publication.) 

Shapiro’s enthusiasm for his subjects is contagious; he makes even the potentially dry stuff like taxonomy and nomenclature engaging. I’ve seen friends open this book at random and laugh out loud. He pulls together a lot of material from the technical literature, much of it new to me. 

For one, there’s the recent study of two lookalike butterflies, the California sister and the Lorquin’s admiral. Really alike: both are dark brown with a broad white diagonal sash across the upper wing surfaces and a bold orange tip to the forewings. I’ve seen speculation for years that the sister was unpalatable to predators, mainly birds, and the admiral mimicked its coloration—a case of Batesian mimicry, named after Darwin’s contemporary Henry Walter Bates, who studied the phenomenon in the Amazon rain forest.  

This made a certain amount of sense: larval sisters eat oak foliage, likely to render them tannic in taste, while larval admirals consume willow leaves. And several of the admiral’s relatives—including the viceroy, which resembles the unpalatable monarch—are known mimics.  

But hard data was lacking. And there was always the possibility that both butterflies tasted bad, and the orange-and-white patterns were mutually reinforcing advertising (a case of Muellerian mimicry.) About six years ago, according to Shapiro, someone asked the birds what they thought. A tasting panel of jays devoured admirals but rejected sisters.  

The Bay Area turns out to be prime territory for butterfly studies.  

We’re at a geographical crossroads, with northern/alpine species like the clodius parnassian in Marin County and semitropical types like the handsome Sonora blue in the South Bay. We have superspecialists: the Lange’s metalmark, which feeds only on naked-stem buckwheat growing in a remnant dune field near Antioch, and other butterflies restricted to serpentine vegetation. We have natives that have shifted hosts, like the anise (or as some purists call it, yampah) swallowtail. We have newcomers like the gulf fritillary, a southeastern butterfly that followed the passionvines west. 

Unfortunately, not all native butterflies have been so adaptable. Manolis illustrates the xerces blue, a former resident of San Francisco’s coastal dunes, although it’s about 66 years too late to see a live one. The Strohbeen’s parnassian of Santa Cruz County hasn’t been observed since Eisenhower was in office. The San Bruno elfin is barely hanging in there. 

Surprises are still possible, though. This, as Shapiro points out, is an area where citizen scientists can make real contributions to the state of knowledge. Patches of serpentine and other specialized habitats remain unexplored: no one has done a butterfly census of Ring Mountain near Tiburon, known for its endemic plants. Life cycle details are undocumented for some species. Shapiro says he has never seen a golden hairstreak visiting a flower, courting, or mating.  

And nets aren’t always necessary. Some butterflies can be cooperative photograph subjects (although others, like the Sara orangetip and its sulphur relatives, never seem to sit still.) Several optics manufacturers offer close-focusing binoculars for butterfly watching.  

I have to admit that butterflies have grown on me over the years; I’ve even reached the point where they can distract me from birds. 

Take Shapiro and Manolis along on your next hike on Mount Diablo and see for yourself.  

I just hope UC Press has somebody working on the moths. 



Joe Eaton’s “Wild Neighbors” column appears every other Tuesday in the Berkeley Daily Planet, alternating with Ron Sullivan’s “Green Neighbors” column on East Bay trees. 


Photograph by Ron Sullivan 

A buckeye, one of the most easily recognizable Bay Area butterflies.