Swallowtail Caterpillars on Parsley: Friend or Foe?

A gardener found numerous caterpillars devouring their parsley and asked for identification. The answer: they are the larvae of swallowtail butterflies, often called "parsley worms." The butterflies laid eggs in July; the tiny hatchlings went unnoticed until they grew large enough to consume visible foliage.

Unless the parsley crop is essential, the recommendation is to let the caterpillars feed. They will soon pupate and emerge as beautiful butterflies. Fresh parsley can be planted in fall for a new harvest after the caterpillars are gone. This is a classic example of sharing the garden with pollinators.

Quick Facts:

• Host plants: Parsley, dill, fennel, carrot tops.
• Lifecycle: Eggs hatch in days; caterpillars feed 2–3 weeks before pupating.
• Adult: Black swallowtail butterfly with yellow and blue markings.

Enjoy the temporary guests—they'll reward you with pollination later!