How One Man Singlehandedly Repopulated a Rare Butterfly Species in His Backyard

Long gone from their home in San Francisco, the California pipevine swallowtail is back thanks to one man transforming his yard into a habitat for them

The iridescent blue wings of the California pipevine swallowtail are considered by collectors to be among the most magnificent in North America.

For centuries the beautiful butterfly thrived in the San Francisco and around the Bay Area. But as the region became increasingly urbanized in the early 1900s, the pipevine swallowtail began to disappear. Today it’s an extremely rare sight.

Aquatic biologist Tim Wong at the California Academy of Sciences has made it his personal mission to bring the butterfly back, and he’s off to a very promising start.

In 2012, he set out on a quest to find California pipevine, the pipevine swallowtail’s sole food source, which had disappeared in tandem with the butterfly in the city.

“Finally, I was able to find this plant in the San Francisco Botanical Garden,” Wong tells “And they allowed me to take a few clippings of the plant.”

Wong propagated the plant in his backyard, weeding, watering and tending it until he had created a pipevine swallowtail paradise.

“I built a large screen enclosure to protect the butterflies and to allow them to mate under outdoor environmental conditions — natural sun, airflow, temp fluctuations,” he says.

“The specialized enclosure protects the butterflies from some predators, increases mating opportunities, and serves as a study environment to better understand the criteria female butterflies are looking for in their ideal host plant.”

After their habitat was ready, Wong scouted our 20 caterpillars from a few residences outside the city with more vegetation and collected them (with permission).

He carefully transported them home and set them loose in their new feeding and mating grounds.

About 6 weeks later, the hungry caterpillars turned into butterflies, and the females began laying tiny red eggs on the stems of the pipevine plant. Success!

After several generations, the butterflies began to multiply exponentially.

Having more than he knew what to do with Wong stared donating caterpillars to the Botanical Gardens, where their food originated from.

At first he brought them in by the hundreds. Now, he brings them in by the thousands, every few months.

While other conservationists have repopulated the pipevine butterfly in neighboring Santa Cruz and Sonoma counties, Wong has made the first and only successful attempt in San Francisco. In the late 1980s, a woman named Barbara Deutsch tried to reintroduce the species with 500 caterpillars, but they vanished after a few years.

Wong attributes his success to the habitat he’s created for the caterpillars. In the past 7 years, he’s cultivated more than 200 California pipevine plants, with no herbicides or pesticides and lots of weeding by hand.

“Improving habitat for native fauna is something anyone can do,” Wong says. “Conservation and stewardship can start in your very own backyard.”