Black Swallowtail Caterpillar

Natural Habitat

Gardens, fields, meadows, and disturbed areas where host plants such as parsley, dill, fennel, carrots, and other plants in the Apiaceae family grow. They are often found in deciduous forests and open fields in North America.

Diet & Feeding

The caterpillars are herbivores and primarily feed on the leaves of plants belonging to the carrot family (Apiaceae), including parsley, dill, fennel, carrot, parsnip, and Queen Anne's Lace. Adult butterflies feed on nectar from a variety of flowers.

Behavior Patterns

Black Swallowtail caterpillars go through several instars (growth stages). Young caterpillars are spiny and black with a white saddle. As they mature, they become smooth, green with black bands and yellow dots. When threatened, they can extrude a pair of orange, Y-shaped scent organs called osmeteria from behind their head, which emit a foul odor to deter predators. They pupate into a chrysalis, which can be green or brown depending on the surroundings, and eventually emerge as adult Black Swallowtail butterflies. The butterflies are active during the day and are strong fliers.

Risks & Benefits

Risks: Caterpillars can defoliate host plants, which can be a concern for gardeners growing herbs like parsley or dill. Benefits: The adult Black Swallowtail butterfly is an important pollinator, contributing to the reproduction of many flowering plants. They are also a beautiful and iconic species that can add aesthetic value to gardens and natural landscapes. They are harmless to humans.

Identified on: 9/5/2025