Black swallowtail butterflies are a large species, with wingspans of up to 4 1/2 inches. They're primarily black in color, with yellow, blue and red markings on their wings. However, like other butterflies, they weren't hatched that way. They go through several stages before they emerge in their adult form.
The first stage in the development of a black swallowtail butterfly is the egg. An adult female will lay her eggs on one of the host plants—plants that the caterpillars will be able to eat and survive on, which include parsley, dill and fennel. These eggs are small and yellow in color. It takes them about three to five days to hatch.
Once the eggs have hatched, black swallowtail butterflies enter their larval phase. The larvae, commonly known as caterpillars, start out small and black, with spines and orange markings. They eat a lot and grow rapidly, shedding their skins as they get larger. As they grow, their appearance changes and they turn pale green with black and yellow stripes.
After the black swallowtail caterpillars have spent two to three weeks eating, and have reached their full lengths, they begin to pupate. During their pupal phase, they wrap themselves in silk and form a chrysalis, attached to a plant by a thread. Safe inside this cocoon, they undergo a metamorphosis, where they change into their adult form. They may stay in the pupal stage all winter and emerge in the spring.
When they're fully developed, adult black swallowtail butterflies break free from their cocoons. On first emerging, these butterflies aren't quite ready to fly. They go through a process known as eclosion, where they pump fluids into their wings so the wings can fully expand. The adult butterflies feed on flower nectar and can be found in meadows, along roadsides and in suburban areas. They mate and the females lay their eggs so the life cycle can begin again.