To paraphrase the conservationist, biologist and author Doug Tallamy, it is only through “small efforts by many people” will we have any hope of saving much of the planet’s biodiversity. This Pittsburgh story exemplifies that, and also nicely illustrates a “butterfly effect” of unintended consequences, the intended pun of which will become evident.
It is the story of a small, beautiful mother, of a kind not seen in Pittsburgh in nearly a century, accidentally becoming an ambassador for how small-scale backyard additions can result in hopeful change and renewal.
I’ve been a biologist in some form since I was first able to toddle into the forests of rural Texas and Arkansas as a child. My later formal training ran the gamut of biological sciences, from ecophysiological studies radio-tracking timber rattlesnakes in the Ozark mountains to obtaining a Ph.D. studying the genetics of heart development.
I’ve been a breast cancer researcher in Pittsburgh for the past dozen years, and while conservation has not been the driving focus of my life, it’s never strayed far from my mind. I would consider myself an inexpert naturalist.
In 2020, as the COVID-19 pandemic took hold and my wife Tamaryn and I were spending massive amounts of time secluded in our small Greenfield backyard, I decided it was time to put more intentional focus into turning our yard into a wildlife-friendly habitat.
When we bought the house in 2017, the backyard was only empty green lawn, which I accentuated with a scavenged birdfeeder stuck in the ground. Many of our immediate neighbors, including an apartment complex, had been cutting down the large trees that initially surrounded us, dousing yards with pesticides, and generally maintaining our local environment as an ecologically dead sea of non-native grass and concrete.
I decided that if I wanted trees and wildlife, I’d have to plant and coax them myself. However, as anyone in Greenfield and much of Pittsburgh can attest, maintaining a garden or landscape often requires wrestling with our beautiful-but-overpopulated white-tailed deer population. I tried to grow a peach tree, and then a cherry tree in its place, but both ended up as sad, little, buck-rubbed, defoliated mockeries of trees. So I decided to research deer-resistant natives.
I immediately came across many sources recommending the pawpaw tree (Asimina triloba), a species which I first learned about on an ecology field trip in the forests of Arkansas in the 1990s.
Cut to June 2024. Our yard has come a long way, hosting an expanding array of native species and sporting four little pawpaw trees and two larger ones. I’ve since learned that the pawpaw is the largest native fruit in North America, often compared to a cross between mango and banana in flavor. It’s described as an “anachronistic” species – a “ghost of evolution,” as it’s thought to have evolved to be consumed and the seeds dispersed in the droppings of now-extinct megafauna such as the mastodon and giant ground sloth that once roamed North America.
Finally — enter the real star of this story — the pawpaw and its close relatives serve as the only larval host for the gorgeous zebra swallowtail butterfly (Eurytides marcellus).
An 87-year absence
A brief but important digression: in April 2024, iNaturalist, a citizen-science app allowing anyone to identify and report sightings of wild plants, animals, and fungi, began its annual competition to see which city can identify the most species. The Pittsburgh effort was largely spearheaded by the manager of ecological restoration for the Pittsburgh Parks Conservancy, Brandon McCracken. He took the initiative to build a WhatsApp chat community to connect essentially every naturalist he could find in the region and encourage participation. Brandon invited me to the group after we had connected through nature posts on Instagram thanks to my interactions with the Pittsburgh Park Rangers. One active member of the chat group, zebra swallowtail expert and archaeological/wetland field technician Gabrielle Marsden, had posted information and videos on her efforts to increase the pawpaw and zebra swallowtail populations in Pittsburgh.
I didn’t initially notice a crucial detail in her posts: Apparently the zebra swallowtail had disappeared from Pittsburgh and the surrounding region almost a century ago! With the rise of the steel mills came the concomitant felling of pawpaw stands and the only host for the zebra swallowtail caterpillars. According to Gabrielle, based on historical records, pawpaw stands once formed a living corridor along which the zebra swallowtail population thrived. Their loss appears to be a classic case of habitat loss and fragmentation, which can be particularly challenging at the edge of a species range. Pittsburgh is currently near the northeastern edge of the zebra swallowtail’s native range.
Cut back to our backyard on a Friday in June. I was sitting and admiring the purple coneflowers, maypops and other flowers now filling our space. My wife got home and sat beside me, and I remarked, “I wish we had more butterflies,” of which I had seen very few. Moments later an eastern tiger swallowtail flitted by. We laughed at the synchronicity of it, and she started to walk inside.
At that moment a flash of white and black appeared in the yard between us and I literally shouted, “Whoa look at that butterfly!” Tamaryn said, “It looks like a zebra!” to which I replied, “Wait a minute! I know what that is. It’s a zebra swallowtail! A woman in my nature chat group was posting about it the other day!” We then chased it around trying to get decent photos and videos with our phones as the butterfly alighted on each pawpaw tree.
While I thought it was super cool, I did not grasp the significance of the butterfly’s appearance. I instantly sent photos to the chat group and within minutes Gabrielle Marsden replied, in all caps, “WHERE ARE YOU?” Gabrielle has been working since 2018 to return the zebra swallowtail to Pittsburgh. Another member of the group, Kevin Keegan, Ph.D., collection manager of invertebrate zoology at Carnegie Museum of Natural History, pulled out and photographed the last known specimen from Pittsburgh, which was found in Highland Park in 1937. As far as I’m aware, this was the last documented sighting in the region – 87 years ago!
Metamorphosis into ‘butterfly daddy’
My primary hobby is woodworking, so I spent that evening researching butterfly enclosures. I spent the next morning hastily building one, had it completed by noon, and found at least a dozen eggs on the young leaves on our pawpaw trees. Gabrielle was at my house not hours after the initial sighting, collecting a handful of eggs to hand-raise as well.
I also discovered a few 1st instar caterpillars — meaning they were in their initial stages of growth — indicating that the female had made at least one previous visit to our yard. The butterfly showed up again three days later, and one final time five days after that, looking more ragged with each visit, for a total of four broods of eggs.
Let me tell you, I did not have “become a butterfly daddy” on my summer bingo card.
I ended up with about three dozen caterpillars. Their daily care required choosing fresh new leaves from the pawpaw trees, placing them in sealed water-filled vials, and carefully transferring each caterpillar to the new leaves. Caterpillars are biological eating machines and only pause their gluttony long enough to shed their skins, so there was a fair amount of “caterpoop” cleanup as well. I watched them develop from tiny black wiggling things 1/3 the size of a grain of rice, go through all five instar stages, form into chrysalises, and then emerge transformed into gorgeous zebra-striped adults, documenting the entire process on my Instagram. As a bonus, many of the chrysalises entered a state of suspended animation called “diapause” and will hopefully emerge next spring.
I’m beyond ecstatic to have successfully raised and released such a unique species and to have brought thousands of people along on the caterpillars’ very hungry journey. It’s quite clear from the reactions and responses that many of us yearn for positive stories about our environment, and for good reason.
Many of the dwindling species on which we humans often unknowingly depend and the vast interconnected webs in which they exist will likely only survive if we as individuals take steps to reconnect the habitats and biological corridors on which they rely. My hope is that this story will inspire others to join this effort to restore and protect at least some of Pittsburgh’s native ecosystem.
I have since learned of several people in our neighborhood who also have pawpaw trees. Perhaps there are more zebra swallowtails around now and this is the beginning of their return to Pittsburgh? Or perhaps she was a single wind-swept individual or escapee from a butterfly exhibit? Regardless, our tiny plot of Pittsburgh serves as a demonstration that if you create wildlife-friendly habitat, even if it’s just a few native flowers or shrubs, life will find it.
Daniel D. Brown is a senior research scientist at the University of Pittsburgh/UPMC’s Institute for Precision Medicine, plus a woodworker/artist at Laughing Mantis Studio and can be reached at danielbrownphd@gmail.com.
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