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Tiger Swallowtails

Overview

The Eastern Tiger Swallowtail (Papilio glaucus) is one of North America's most recognizable butterflies. Known for its striking yellow and black striped wings, this butterfly is widely distributed across the eastern United States and parts of Canada. It can be found in a variety of habitats, from woodlands to suburban gardens, where its larvae feed on various host trees. Eastern Tiger Swallowtails are important pollinators and are often seen in flight during the warmer months.

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Description and Species

Description
Tiger Swallowtails have large, distinctive wings with black tiger-like stripes on a yellow background. Their forewings are primarily yellow with black stripes, while their hindwings are also yellow but feature blue and orange spots near the edges. The butterfly's characteristic 'tails' on the hindwings give it the appearance of a swallow, which is the origin of its common name.

Male vs Female
The sex of adult Tiger Swallowtails is easy to distinguish. Males are slightly smaller, and females have blue iridescent scaling on the hindwings, which males do not.

There is also a dark morph of female Tiger Swallowtails, where the yellow pigments are replaced by black pigments. The butterfly's genetics only allow this morph to occur in females. These dark morphs look similar to Pipevine Swallowtails, but the stripes are still visible-though more difficult to see.

Species
There are a few very similar species that have overlapping ranges and sometimes produce hybrids.

The Eastern Tiger Swallowtail (Papilio glaucus) is the most common species in the United States. This species is found in all states east of the Rocky Mountains.

The Western Tiger Swallowtail (Papilio rutulus) is nearly identical to the Eastern species but is found in the Rocky Mountains and westward.

The Canadian Tiger Swallowtail (Papilio canadensis) is found mainly in Canada and bordering states. It is slightly smaller and paler than the Eastern species.

The Appalachian Tiger Swallowtail (Papilio appalachiensis) is a cross between the Canadian and Eastern species. It is mainly found along the Appalachian mountain chain. This species seems to prefer only the wild black cherry (Prunus serotina) that grows in Appalachia as a host plant.

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Host Plants

The larvae of Tiger Swallowtails feed on many native species of trees, including the Tulip Tree (Liriodendron tulipifera), native Cherry (Prunus spp.), Hop Tree (Ptelea trifoliata), Sassafras (Sassafras albidum), Sweetbay Magnolia (Magnolia virginiana), Wild Black Willow (Salix nigra), Ash trees (Fraxinus sp.), and Cottonwoods (Populus sp.). The number of different host trees explains why this butterfly is so common. The adults lay their eggs on these trees, which provide a food source for the caterpillars.

Although many of these trees get quite large, there are some species that are small and easy to grow in a yard with limited space.
Plant Natives and they will come - Learn about the smaller Sweetbay Magnolia and Chokecherry host plants.

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Habitat and Range

Eastern Tiger Swallowtails are found throughout the eastern United States, ranging from southern Canada to Florida and as far west as the start of the Rocky Mountains. They thrive in a variety of habitats, including deciduous forests, woodlands, and native plant gardens, and can often be seen in suburban areas if their host plants are found. The presence of open fields or areas with access to nectar-rich flowers also supports their populations. Although not considered endangered, due to loss of habitat and host plants, these butterflies (along with most butterfly species) have experienced a sharp decline of over 30% over the past 20 years.

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Adults and Flights

Adult Eastern Tiger Swallowtails only live around 1-2 weeks and are active from spring through fall, with multiple generations emerging throughout the warm months. In the north, they typically have 2 flights per year, while in the south, they may have 3 flights, depending on the weather. The butterflies are strong fliers and can cover large areas in search of nectar and host plants. They are often seen feeding on native flowers like milkweed and coneflowers. Males patrol for females, while females search for suitable host plants to lay their eggs.

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Spicebush Caterpillars - Instars

1st to 3rd Instars

Eastern Tiger Swallowtail caterpillars go through five instars (molts). The caterpillars look similar to Spicebush Swallowtails. In their early instars, they resemble bird droppings and are small and brownish with a prominent white V marking near their 'necks.' As they molt, tiny blue dots appear on them, which is the easiest way to distinguish them from a Spicebush Swallowtail. By the 4th instar, they are greenish in color and retain a white patch on their backs and tail. The 5th instar caterpillars are large and green with a distinctive black and yellow band and blue spots near the false neck, and the false eyes are much more pronounced. To tell the difference between a 4th and 5th instar Tiger Swallowtail from a Spicebush Swallowtail, caterpillar is they do not have the double set of 'eyes' like Spicebush caterpillars do. Their main 'eyes' are also smaller, and they have a ring around their neck and have the tiny blue dots.They often do not roll or fold leaves like the Spicebush Swallowtails; however, 4th and 5th instars will sometimes roll a leaf for cover.

Like the Spicebush Swallowtails, when they are about to pupate into a chrysalis, they can undergo a color change, turning brown to match the twig they will pupate on. They will purge their waste and undergo a color change in a matter of hours. Once complete, they descend to the ground and look for a twig to pupate into a chrysalis. They usually travel 10 - 30 feet from their host tree to find a suitable location to pupate, such as a nearby bush, twigs, or leaf litter. The chrysalises are usually brown but can sometimes be green, depending on the conditions and surroundings.

They stay in the chrysalis for approximately 10-20 days, then emerge as butterflies. In the fall, they will stay in the chrysalis through the winter. These times are very approximate, some may stay in the chrysalis much longer before emerging.

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How to Attract and Support Tiger Swallowtails

To attract Tiger Swallowtails to your native garden or backyard, you need a variety of native nectar producing plants. I've noticed favorites are Joe-Pye Weed, Milkweed, and Coneflower. There are dwarf varieties of Joe-Pye Weed that do not get as tall, which are more suitable for small spaces.

If you want to boost their population, plant a host plant. Although their host plants are trees, this does not mean you need a large space. There are a few hosts that stay small. Sweetbay Magnolia (Magnolia virginiana), Chokecherry (Prunus virginiana), and the Little Volunteer cultivator of the Tulip Tree all stay under 25 feet tall, and can be pruned to keep even smaller. I have a Little Volunteer Tulip Tree that I even pruned into a shrub form. You can also prune the Chokecherry into a shrub. Out of these three smaller hosts, I've noticed they prefer the Chokecherry Trees and the Sweetbay Magnolias the most.

If you have room, a wild Black Cherry (Prunus Serotina) is the best option, as it supports hundreds of lepidoptera (butterflies and moths), and appears to be one of the Tiger Swallowtails favorites.

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Sweetbay Magnolia (Magnolia virginiana) Host Plant:

Chokecherry (Prunus virginiana) Host Plant:

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Recommended Butterfly Rearing Items:

Note: Raise butterflies for educational purposes only as it's best to leave them on the native plant. If you do raise them, please keep them outside. do not raise them indoors.

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Recommended Wildlife Restoration Books:

These books below are by Doug Tallamy, a renowned entomologist and ecologist, widely recognized as the leading advocate for promoting native plantings in yards to support biodiversity and wildlife conservation.

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