A Tale of Two Butterflies

glaucopsyche_xerces

Pinned specimens of the Xerces Blue in the Field Museum of Natural History. Photo by Brianwray26, licensed under Creative Commons via Wikipedia.

There are no graceful ways to mention extinct species in casual conversation. Years ago, on a visit to San Francisco, a local friend asked what I thought of Golden Gate Park. “You’re a naturalist, right—isn’t that just your thing?” I made the mistake of answering honestly. “It’s very pretty,” I agreed, “but there are too many eucalyptus trees and I think it would be better if the Xerces Blue were still around.” Awkward silence followed. Our conversation had taken a sudden nosedive, just like the population of Xerces Blue.

The Xerces Blue (Glaucopsyche xerces) was a small, delicate butterfly belonging to a group poetically dubbed the gossamerwings. Tiny flecks of iridescent sky on the wind, they bumbled low over the sand dunes along the Pacific coast in search of their host plants, weedy, insignificant-looking vetches, or wild peas. Aside from a few naturalists at the nearby California Academy of Science, nobody paid much attention to them. Life went on.

As the developing city of San Francisco swelled and grew, enterprising settlers changed the environment to suit themselves. They filled in the marshlands on the eastern edge of the peninsula, planted windbreaks of eucalyptus and Monterey pines to stabilize the dunes for Golden Gate Park, and paved over everything in between. The population of the Xerces Blue flickered like a soap bubble, and abruptly vanished. The last one was spotted in 1943. The very traits that allow the Xerces Blue to flourish as a species—their isolated population, their dependence on specific plant species—meant their populations could not recover from any damages. Once they were gone, they were just… well, gone.

Unlike most extinct insects, which vanish unnoticed and unmourned by humans, the Xerces Blue enjoys a moderate degree of fame and notoriety in its afterlife. Officially, it was the first insect species documented to become extinct from habitat loss and urban development. And it became the namesake for the Xerces Society, a conservation non-profit dedicated to preventing any further insect extinctions from happening. But unlike the passenger pigeon or the dodo, there are no plaques, no statues, no monuments, and its name is barely mentioned in popular literature. All that remains are occasional references in books, a handful of specimens in sealed cases in natural history museums and perhaps a few flickers of memory from those lucky enough to see one alive. On my visit to Golden Gate Park, I grieved the loss of the Xerces Blue. The possibility of ever seeing one alive was gone now, and it felt unbearably tragic.

Even as I found myself enjoying the city of San Francisco and all it had to offer (including Golden Gate Park, despite myself), I could not help but question—was it really always a choice between urban development and natural history? Was the destruction of the Xerces Blue inevitable? What could we do differently in the future?

Another species of native butterfly offers new insights into my questions. The California pipevine swallowtail (Battus philenor hirsuta) is a smaller, bulkier subspecies of the more widely distributed pipevine swallowtail, found only in California. The caterpillars in their later instars memorably resemble black and orange alien slugs, waving poisonous tentacles as a deterrence to predators; the pupae bear an uncanny resemblance to Metapods from Pokemon Go. The caterpillars only feed on the endemic California pipevine (Aristolachia californica), and their populations were crashing along with that of their food plant. It seemed like the usual extinction narrative was up and running. I braced myself for the worst.

But the story abruptly changed directions. Tim Wong, a biologist working in Golden Gate Park, started growing California pipevine and raising swallowtails in his backyard. The population of swallowtails in the city swelled rapidly. The more pipevine he and others planted in the area, the more butterflies there were. The California pipevine swallowtail is still threatened—there are no real ends in this kind of work—but at least this was a step in the right direction. There is hope. Not too far from the last home of the Xerces Blue, another threatened butterfly species is rebounding. For me, haunted by dreams of vanished butterflies, it felt like a kind of absolution. Maybe this time we wouldn’t screw up.

I think it’s safe to say that no one loved the Xerces Blue the way Tim Wong loves the California pipevine swallowtail—not, at least, until it was too late. Certainly, the simpler biology and wider range of the swallowtail made it easier for its populations to recover. But having human champions, people who were too crazy and too dedicated to sit back and do nothing, turned the tide in San Francisco. And what exactly brought the butterflies back? Creating habitat. Propagating their host plant, California pipevine, planting it in gardens and raising caterpillars. Nothing too big or dramatic. Just small changes, expanded over a wider scale. Anyone could do it, and someone did. And everything changed as a result.

Actions like these remind me that my dreams of gardens full of life and hope are not pipe dreams—or pipevine dreams, for that matter. They offer us an alternative to the usual doom-and-gloom framework, the long, slow, slide or the short, abrupt route to to extinction. They depend not on helplessness, but on personal involvement, personal responsibility, personal action—a reminder that all our actions matter. If everyone cared about just one species or place the way Tim Wong cared about the California pipevine swallowtail—enough to go out of their way to help them flourish in their own community, literally their own backyard—the world would be a vastly different place. Certainly more diverse, anyway. And if just a few people cared—well, that, too, would make a difference between life and death, endings and beginnings, at least for the time being.

Looking back to our awkward conversation in San Francisco, I now know what I would say to my friend, and to everyone else who cares to listen:

“Somewhere, not too far away, there is something so precious you cannot bear to lose it. Find it. Help it. Plant the seeds in your garden; make space for it in your heart. All is not yet lost. All is not yet gone the way of the Xerces Blue. Those that remain, like the California pipevine swallowtail, can still come back to us. All they need is the opportunity. Let us help them come home.”

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