Eastern Tiger Swallowtails Return to the Hill Country

The Eastern Tiger Swallowtail (Papilio glaucus) is a species of swallowtail butterfly native to North America. It is one of the most familiar butterflies in the eastern United States.

The Eastern Tiger Swallowtail was once considered to be a single species, but is now divided into three species; the Canadian Tiger Swallowtail (Papilio canadensis), the Eastern Tiger Swallowtail, and the Appalachian Tiger Swallowtail (Papilio appalachiensis). These three species are very similar to one another, and can be hard to tell apart. The Eastern Tiger Swallowtail has a wingspan of 7.9 to 14 centimeters (3 to 5.5 inches). The adult male is yellow, with black "tiger stripes". There are two morphs of adult females, a yellow one and a dark one. The yellow one is similar to the male, except there is a patch of blue on the hind wing. In the dark morph, the yellow areas are replaced by dark gray or black.^[2]

The Eastern Tiger Swallowtail can be found in much of the eastern United States. It is generally common throughout its range, and can be found in various habitats, such as woodlands, woodland openings, woodland edges, fields, open areas, rivers, creeks, roadsides, gardens, urban parks, and city yards.

The female Eastern Tiger Swallowtail lays her green eggs singly on host plant leaves. Young caterpillars are brown and white, mimicking bird droppings. Older caterpillars are green, with two black, yellow, and blue eyespots on the thorax. It is also spotted with light blue on the abdomen. The caterpillar will turn brown just before pupating. It will reach a length of 5.5 centimeters (2.2 inches). The chrysalis varies, from a whitish color to dark brown. It is usually patched with green and other dark markings.

Taxonomy

The Eastern Tiger Swallowtail was formerly considered to be a single species with a vast range into northern Canada and the eastern United States. It has now been divided into a total of three species; the Canadian Tiger Swallowtail, which is found in Canada; the Eastern Tiger Swallowtail, which is found in the eastern United States; and the Appalachian Tiger Swallowtail, which is found in the Appalachian Mountains.

Some taxonomists place the Eastern Tiger Swallowtail, along with the other tiger swallowtails, in the genus Pterourous.

Description

The Eastern Tiger Swallowtail has a wingspan of 7.9 to 14 centimeters (3 to 5.5 inches). Adult males are yellow, with four black "tiger stripes" on each fore wing. The trailing edges of the fore and hind wings are black with yellow spots. On the inner margin of the hind wing, there are small red and blue spots. On the underside of the fore wing margin, there is a yellow bar that is broken up into spots. This broken bar is present in both sexes.

There are two morphs of adult females, a yellow one and a dark one. The yellow morph is similar to the male, except that the hind wings have an area of blue between the black border and the main yellow area. In the dark morph, the yellow is replaced with a dark gray to a black color. A shadow of the "tiger stripes" can still be seen on the underside of some dark females. The dark form is more common in the southern portions of the range, especially in areas also inhabited by the poisonous Pipevine Swallowtail (Battus philenor), which it seems to mimic.

Similar species

The Eastern Tiger Swallowtail has two similar species in its range: the Canadian Tiger Swallowtail and the Appalachian Tiger Swallowtail. They can be hard to distinguish from one another.

The Canadian Tiger Swallowtail is usually smaller. The yellow marginal bar on the underside of the fore wing is not broken up into spots. On the underside of the hind wing edge near the abdomen, there is a black stripe. This stripe is thicker in the Canadian Tiger Swallowtail. Intermediates between the Eastern Tiger Swallowtail and the Canadian Tiger Swallowtail are known to occur.

The Appalachian Tiger Swallowtail is larger than the spring brood of the Eastern Tiger Swallowtail. Appalachian females do not have a dark form. The blue-and-black area on the underside of the hind wing is reduced.

Range and distribution

The Eastern Tiger Swallowtail is found from southern Vermont down to Florida west to eastern Texas and the Great Plains. It is generally common throughout its range. It is rarer in southern Florida and absent from the Florida Keys. There is an isolated population in Mexico.

State butterfly and insect status

The Eastern Tiger Swallowtail is the state butterfly of Alabama, Delaware, Georgia, and South Carolina, and is the state insect of Virginia.

Habitat

The Eastern Tiger Swallowtail can be found almost anywhere deciduous forests occur. Some of its common habitats include, woodlands, woodland openings, woodland edges, fields, open areas, rivers, creeks, roadsides, gardens, urban parks, and city yards.

Flight period

The Eastern Tiger Swallowtail is seen from May to September in the northern portion of its range, from April to October in the middle portion, and from February to November in the southern portion. There are two broods in the north, and three in the south.

Adult food sources

The Eastern Tiger Swallowtail uses a wide range of food sources. Most adults prefer to nectar on sturdy plants. Males are attracted to mud, damp gravel, and puddles, extracting sodium from these sources. Males can often be seen in large congregations puddling, especially in the spring. Adults have also been seen feeding on dung, carrion, and urine.