Monarchs are in the news a lot lately, but they’re not the only butterfly out there – or even (arguably) the most spectacular. Big and flashy, swallowtail butterflies are a delight in the butterfly garden, and everyone would love to attract more of these beauties. Here’s a quick run-down of the most common swallowtail butterflies in the U.S. (some are also found in southern Canada).
The graceful sailing flight of a Tiger Swallowtail against the blue sky is a lovely sight, and though they’re more frequently found in wooded areas (they generally host on trees), they’re common in the flower garden too. There are a variety of species of tiger swallowtails around the country, all of which look fairly similar. In the east, look for the Eastern Tiger Swallowtail (Papilio glaucus), Canadian Tiger Swallowtail (Papilio canadensis), and Appalachian Tiger Swallowtail (Papilio appalachiensis). Out west, you’ll find the Western Tiger Swallowtail (Papilio rutulus) and the Pale Swallowtail (Papilio eurymedon). In some areas, females are black with tiger stripes only faintly visible in the bright sun.
Black Swallowtail (Papilio polyxenes) larvae are often known as “parsley caterpillars” since that’s one of their most common host plants. They also host on dill, fennel, Queen Anne’s Lace, and common rue. This swallowtail butterfly is found in much of the U.S. with the exception of the northwest. You can tell males from females as females have a band of irridescent blue on their hindwings, while males have a band of yellow instead.
Pipevine Swallowtails (Battus philenor) are found throughout the eastern U.S. and through the southwest to California. They host on pipevines (Aristolochia sp), as their name indicates, and males are a beautiful iridescent blue (females are a duller black). They lay bright red eggs in groups on their host plants, and their caterpillars are extremely fast moving.
As the name implies, the Giant Swallowtail (Papilio cresphontes) is the largest swallowtail butterfly in the U.S., with a wingspan of up to 6 inches. This butterfly is an excellent example of countershading, being dark on the topsides of their wings and bright yellow on the bottom. This allows them better camouflage against predators. Giant Swallowtails lay eggs on citrus trees, as well as prickly ash and common rue. Their caterpillars also display excellent camouflage, looking exactly like fresh bird droppings.
Spicebush Swallowtails (Papilio troilus) are found in the eastern half of the country, where their range overlaps with the extremely similar-looking Black Swallowtail (see above). You can easily tell a Spicebush Swallowtail from a Black Swallowtail if you can get a close look; Black Swallowtails have a tiny black dot in the orange circle at the base of their lower wing, while Spicebush do not. As the name might suggest, this swallowtail butterfly hosts on Spicebush, as well as red bay, camphor, sweet bay, and tulip tree. Their caterpillars are leaf-rollers, and have large eyespots to scare off predators.
Probably the most spectacular of the swallowtail butterflies, the Zebra Swallowtail (Protographium marcellus syn. Eurytides marcellus) flies in the eastern half of the country. However, it is one of the rarest swallowtail butterflies for most of us, since it’s usually only found in great numbers where its host plant, pawpaw (Asimina sp.) also thrives. Though one of the smaller swallowtails, the long tails and distinctive zebra striping make this butterfly a stunning sight. Where pawpaw grows in groves, this butterfly will be very common. For the rest of us, it remains an occasional cherished sight.
Want more tips for attracting swallowtails? Try this list of Top 10 Plants for Swallowtails from the September 2015 issue of Birds & Blooms Extra.