Since spring is solidly here for us here in the Northeast and people are out exploring their gardens, this caterpillar identification key might come in useful: Caterpillars of the Eastern Forests. The Eastern Black Swallowtail (Papilo polygenes) caterpillar in the photo was on a plant in the retail area at Garden in the Woods. Keep your eyes open, you never know what you’ll see!
The larval host pants for the Eastern Black Swallowtail include plants in the carrot and parsley (Apiaceae) family: parsley, Queen Anne’s lace, wild carrot, celery, dill, and fennel. Many of those plants are not native, and it is important to note that many of the native plants in the Apiaceae family are quite poisonous, such as poison hemlock, water hemlock, and cow parsnip. I mention this because many species need wild spaces where native plants that are not suitable for gardens or cultivated spaces can grow.
The adult host plants for nectar include: pawpaw, red clover, phlox, asclepias, asters, and thistles.