Black Swallowtail Caterpillars and What They Eat In Our Garden

Black swallowtail butterfly caterpillars are fascinating creatures with a dynamic life cycle. These caterpillars are often identified by their vibrant appearance, featuring green bodies with black bands and yellow or white spots. As they grow, they undergo several stages known as instars, each marked by changes in their coloration and patterns.

An interesting characteristic of black swallowtail caterpillars is their defense mechanism: they possess a structure called an osmeterium, a forked organ that resembles small orange or yellow "horns." When threatened, they extend this organ, which emits a strong odor to deter predators.

These caterpillars feed primarily on plants in the carrot family, such as dill, parsley, fennel, and Queen Anne's lace. This choice of diet plays a critical role in their growth and development, enabling them to transition into their next phase as a chrysalis before emerging as a stunning black swallowtail butterfly.