Black Swallowtail Caterpillar

Found in a variety of habitats where their host plants grow, including gardens, fields, meadows, farmlands, and roadsides.

The caterpillars are herbivores, primarily feeding on plants in the carrot family (Apiaceae), such as parsley, dill, fennel, carrots, and parsnips. They also feed on citrus family plants (Rutaceae) and some plants in the rue family.

As caterpillars, they feed voraciously on their host plants. When disturbed, they can evert an orange, Y-shaped organ called an osmeterium from behind their head, which emits a foul-smelling substance to deter predators. After a period of growth, the caterpillar will pupate, forming a chrysalis. The adult butterfly emerges from the chrysalis.

Generally beneficial to the ecosystem as they are pollinators in their adult stage (butterflies). The caterpillars can be considered pests by gardeners due to their feeding on cultivated plants like parsley and dill, but the damage is usually minor and they contribute to biodiversity.