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How One Man Brought the Butterflies Back to the San Francisco Botanical Garden

As a part-time volunteer, Timothy Wong hatched a big idea to help the California pipevine swallowtail flourish in Golden Gate Park.


Wong gets a faceful.

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The California pipe vine swallowtail is known for its deep-blue wings. As a caterpillar, it is a prickly, black-and-orange creature.

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The caterpillar lays eggs on the leaves of its host plant, the California Dutchman's-pipe, in clutches of between a half dozen and about 30.

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Editor’s Note: This is one of many stories about Golden Gate Park that San Francisco is publishing over the next month as part of the June 2017 issue. To read stories as they become available online, click here.

It’s a Friday
morning in February in the nearly empty San Francisco Botanical Garden, and it’s pouring—absolutely pouring—rain when I first meet Timothy Wong. He’s covered head to toe in rain slicks, mud caked onto his boots and knees, and yet he’s unerringly upbeat. He greets me near the entrance to the California Native Garden and leads me tramping through overgrown thatches of weeds, behind a nursery, along an ugly stretch of cyclone fencing. My wife and I walk through the garden frequently, but we’ve never been here.

I’m on the hunt for big, spiny, black-and-orange caterpillars. They’re kind of ugly, hard to find, and—in this weather at least—seem unworthy of the effort. Not to Wong, though: This thicket of vines is the habitat Wong has spent years creating for one particular species of butterfly. Each Friday, Wong shows up to pull the weeds that choke out the California Dutchman’s-pipe, or pipe vine—the sole suitable host for the California pipe vine swallowtail, or Battus philenor hirsuta. Most of Wong’s work, it turns out, revolves around pulling weeds.

If that seems like a strange passion project, well, sure. But it’s all in the service of attracting and offering refuge to the swallowtail. It is, indeed, a beautiful creature: The male has deep-blue wings, specked with circular orange spots. Among butterfly collectors, the California pipe vine swallowtail is prized for its coloring.

But whatever glamour there may be in seeing a wave of indigo flutter past is sorely missing today, replaced only by rain and mud and prickly blackberry vines. Still, this is the price to be paid for attracting the beauty. Once widespread throughout the Bay Area, the insect is now locally rare in San Francisco, where human development and invasive species have conspired to decimate suitable areas for its host plant to grow. That’s in part because the vine is a fickle plant: In order for it to attract the butterflies, it requires sunlight, a proximity to water, and, crucially, time. (It can take up to a decade for the vine to mature enough to attract the butterflies.) Other than in the Botanical Garden’s artificial environs, the area around Lake Merced is one of only a few places it seems to flourish.

Wong is technically a volunteer at the garden; he’s really a biologist at the California Academy of Sciences. But he’s been a butterfly enthusiast since childhood and enamored of the pipe vine swallowtail for years. Its rarity piqued his interest: Paradoxically, it’s incredibly hard to find, and yet once you do, it’s almost impossible to miss. He was drawn to it at once.

So in 2012, he approached the Botanical Garden about creating a habitat for the species, which they encouraged. It wasn’t the first time the idea had been raised: Another enthusiast, Barbara Deutsch, had made a similar effort to reintroduce the butterflies there many years earlier. That population ultimately vanished after a year or two, but the vine she’d planted (and other vines that date back to the garden’s founding in the 1950s) remained, albeit shrouded in weeds.

That was enough to get started. Using clippings of the garden’s pipe vine and donated caterpillars from other Bay Area collectors, Wong was able to establish a small colony in his Hillsborough backyard, where they mated and pupated inside a screened-off greenhouse. Once the colony numbered in the thousands, he began releasing some of them in the Botanical Garden. Wong says he made a key discovery in the early days: that the females preferred to lay their eggs on pipe vine that was close to the ground and in direct sunlight. Most of the mature vines in the garden were lost in the shade under a layer of grasses. That meant clearing more weeds. “The Botanical Garden was already set, or had the foundation, to be a butterfly habitat,” Wong explains. It just needed some TLC.

Today the garden’s swallowtail population is flourishing—Wong estimates that the Botanical Garden now boasts the largest and most inviting stand of California Dutchman’s-pipe in the city. Wong’s goal is to see the species spread outward from the garden and across the city, connected by a network of backyard plantings of the pipe vine.

It’s an ambitious dream, and one that may be hard to realize: The vine itself is disappearing from San Francisco, and its resurrection would rely on individuals planting it in their home gardens. Then there’s another problem: The swallowtail isn’t technically an endangered species—and thus doesn’t enjoy the protections (or publicity) that status entails. New building developments are free to clear the pipe vine plant if necessary. (On the other hand, a well-promoted effort to secure endangered status for the monarch butterfly—with its orange-and-black stained-glass wings—has led scores of enthusiasts to rally behind its recovery.)

In the face of all that—and especially now, as he yanks weeds during this downpour—Wong’s quest seems even more quixotic. I try to form the right question to pose to him to get at the implicit why. Why this one species? Why all this trouble?

It seems not to register. Wong tends not to dwell on those questions. For him, the intrinsic value of the species doesn’t require explanation. He doesn’t tell me about the butterfly’s place in plant cross-pollination, or how it engenders a healthy local biodiversity in our plants. It’s just beautiful, exotic, pleasant to look at. That alone makes it worth saving. Whatever value it adds to our city is indefinable. How do you put a price on a shot of color, a bit of vibrancy, the sight of a profoundly blue butterfly flitting across your field of vision?


Originally published in the June issue of San Francisco 

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