Head to head
Black Swallowtail vs Spicebush Swallowtail
A black swallowtail and a spicebush swallowtail are both dark-winged North American butterflies whose caterpillars rely on genuinely elaborate defences, yet the two have settled on completely different survival tricks despite sharing the same general swallowtail body plan.
| Black Swallowtail | Spicebush Swallowtail | |
|---|---|---|
| Scientific name | Papilio polyxenes | Papilio troilus |
| Caterpillar defence | Foul-smelling forked osmeterium | Leaf shelter plus false snake eyes |
| Host plants | Parsley, dill, Queen Anne's lace | Spicebush, sassafras |
| Caterpillar nickname | Parsleyworm | None notable |
| Adult wing pattern | Black with yellow spot rows | Dark with pale edge spots, blue-green wash |
| Habitat | Grassland and gardens | Forest and woodland edges |
| Generations per year | Multiple | Multiple |
| Conservation status | Least Concern | Least Concern |
Black Swallowtail vs Spicebush Swallowtail: common questions
How do the black swallowtail and spicebush swallowtail caterpillars defend themselves differently?
A black swallowtail caterpillar extends a bright orange, forked organ called an osmeterium that releases a foul smell when threatened, while a spicebush swallowtail caterpillar instead relies on hiding inside a self-made folded leaf shelter and on two large false eyespots that give it a startling snake-like appearance, a visual bluff rather than a chemical one.
Why is the black swallowtail caterpillar called the parsleyworm?
The black swallowtail caterpillar is nicknamed the parsleyworm because it commonly feeds on garden parsley and related plants such as dill and Queen Anne's lace, a host plant preference the spicebush swallowtail does not share, since its caterpillars instead feed specifically on spicebush and sassafras.
Which of these two caterpillars is easier to raise at home?
The black swallowtail is generally considered easier to raise at home, since its caterpillars readily accept common garden herbs such as parsley and dill, while the spicebush swallowtail caterpillar requires access to its more specific host plants, spicebush or sassafras, which are less commonly grown in home gardens.