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The Eastern tiger swallowtail (Papilio glaucus) is a species of swallowtail butterfly native to eastern North America. It is one of the most familiar butterflies in the eastern United States, where it is common in many different habitats. It flies from spring to fall, during which it produces two to three broods. Adults feed on the nectar of many species of flowers, mostly from those of the Apocynaceae, Asteraceae, and Fabaceae families. P. glaucus has a wingspan measuring 7.9 to 14 cm (3.1 to 5.5 in). The male is yellow with four black "tiger stripes" on each fore wing. Females may be either yellow or black, making them dimorphic. The yellow morph is similar to the male, but with a conspicuous band of blue spots along the hindwing, while the dark morph is almost completely black. The green eggs are laid singly on plants of the Magnoliaceae and Rosaceae families. Young caterpillars are brown and white; older ones are green with two black, yellow, and blue eyespots on the thorax. The caterpillar will turn brown prior to pupating. It will reach a length of 5.5 centimetres (2.2 in). The chrysalis varies from a whitish color to dark brown. Hibernation occurs in this stage in locations with cold winter months.
P. glaucus is found in the eastern United States from southern Vermont to Florida west to eastern Texas and the Great Plains. It is common throughout its range, although is rarer in southern Florida and absent from the Florida Keys. In 1932, a single specimen was collected in County Wicklow, Ireland. It is believed to have been an accidental introduction from North America. P. glaucus can be found almost anywhere deciduous forests occur. Common habitats include woodlands, fields, rivers, creeks, roadsides, and gardens. It will stray into urban parks and city yards. Because it has adapted to many different habitats and host plants, P. glaucus is a generalist, and is not considered threatened.
Pictured is a female.