Number 9 • 2002 • Jeffrey K. Barnes

Black swallowtail caterpillar (parsleyworm)
Order: Lepidoptera
Family: Papilionidae
Genus and species: Papilio polyxenes Fabricius

Parsleyworm with exposed osmeteria  Parsleyworm on dill

Caterpillars of black swallowtail butterflies, Papilio polyxenes, are various shades of green, with narrow black bands on each body segment. The black bands are interrupted by yellow-orange dots. The caterpillars, which can reach 2” in length, consume leaves and flowers of various plants in the carrot family (Apiaceae), including cultivated carrot, parsley, dill, and fennel. Older larvae often prefer the inflorescence. These caterpillars can destroy a home gardener’s crop quickly if they go unnoticed. This species spends the winter in the pupal stage inside a chrysalis. Adults, which are black with yellow markings near the margins of the fore and hind wings, and more limited blue and red marking on the hind wings, emerge in the spring and seek a host plant on which to lay eggs. The caterpillars have a forked, glandular process behind the head that can be everted to emit a strong odor distasteful to predators.

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Butterflies and moths of North America