Black swallowtail butterflies are among the easiest to attract to your garden. We began with a few chrysalises a friend gave us, which we put in our mesh butterfly garden. They can take months to hatch! They eat parsley, dill, fennel, and carrot greens. We grow parsley and they devour it on our deck. Once you release the first few butterflies, you'll have many in years to come if you provide a food source. These are the second instar or growth stage of black swallowtail caterpillars.