One of Bernheim’s many butterfly species is the unmistakable zebra swallowtail. This butterfly is easily identified by its black stripes on white wings, with a patch of red near its long tail. The zebra swallowtail native range stretches all throughout the eastern US, where it prefers forested riparian areas, wetlands, and other habitats with plenty of water. Bernheim’s natural areas are a complex mosaic of habitats that include these abundant water sources. Its desired habitat gets even more specific in that the zebra swallowtail must live close to the famous pawpaw tree (Asimina triloba).
The pawpaw, which produces the largest tree-grown, edible, native fruit in the US, is the only leaf that zebra swallowtail caterpillars eat. In addition to using the leaves for food, the butterfly also lays its eggs on the underside of the leaves, one egg per leaf. After a couple of weeks, the eggs hatch, and the caterpillars then have their own leaves to munch on. When the caterpillar finishes molting, it pupates. The color of the camouflaged chrysalis is usually green if the process began on a green leaf and brown if on a dead leaf, likely determined by daylight length (spring and summer generations being green, autumn generations being brown). Given time, out from the chrysalis emerges a new zebra swallowtail, ready to continue the cycle.
Bernheim’s ecosystems are complex; one species depends on another, which depends on another, and so on. The natural processes and systems happen perpetually, whether we’re aware or not. Slow down sometime and watch a butterfly for a bit. And if you’re out in Bernheim’s natural areas, and you see a zebra swallowtail flying around or huddled with other butterflies in the mud, keep an eye out for its favorite tree.
