Papilio glaucus
One of the most familiar and widespread butterflies in eastern North America, known for its large yellow-and-black striped wings and broad host plant range. A generalist larval feeder on trees in Magnoliaceae, Rosaceae, and Lauraceae families, reaching southern Ontario at the northern edge of its range.
Seasonal Activity
Diet
Foliage of tulip tree, black cherry, ash, sassafras, magnolia, and other deciduous trees (larva); nectar from Apocynaceae, Asteraceae, and Fabaceae flowers (adult)
Lifecycle
Two broods per year in the north, three in the south. Eggs laid singly on host leaves. Early-instar caterpillars are brown with a white saddle, mimicking bird droppings. Later instars are green with two black, yellow, and blue false eyespots on a swollen thorax. An orange osmeterium is everted when threatened. Pupae overwinter in a chrysalis attached to tree trunks or ground litter. Adults emerge in spring and fly from May through September in Ontario.
Ecology
Native Habitats
Details
Description
The Eastern Tiger Swallowtail (Papilio glaucus) is one of the most recognizable butterflies in eastern North America, with a wingspan of 7.9-14 cm. Males are bright yellow with four black "tiger stripes" on each forewing and small red and blue spots along the inner hindwing margin. Females are sexually dimorphic: the yellow morph resembles the male but with a conspicuous band of blue spots on the hindwing; the dark morph is almost entirely black with subtle tiger-stripe shadows visible on the underside. The dark morph females employ Batesian mimicry of the toxic Pipevine Swallowtail (Battus philenor).
The species is ranked Secure (G5) globally by NatureServe and is the state butterfly of Alabama, Delaware, Georgia, North Carolina, and South Carolina. In Ontario, it is common throughout the Carolinian zone and reaches the northern limit of its range in the province. It is widely considered the most polyphagous of all 560+ swallowtail species.
Lifecycle
Eastern Tiger Swallowtails produce two broods per year in the north, with adults flying from May through September in Ontario. Eggs are round, green, and laid singly on host plant leaves. Early-instar caterpillars are dark brown with a prominent white saddle, closely mimicking bird droppings. After molting to the fourth instar, the caterpillar becomes bright green with two black, yellow, and blue false eyespots on an enlarged thorax — a convincing snake mimic. When threatened, the caterpillar everts a bright orange, forked osmeterium that emits foul-smelling terpenes to repel predators.
Pupation occurs in a chrysalis attached by a silk girdle to tree trunks, fence posts, or ground litter. The chrysalis varies from whitish to dark brown and overwinters in cold climates. Adults are powerful fliers, often soaring above the tree canopy. Males engage in mud-puddling to obtain minerals, while both sexes nectar extensively on sturdy flowers in pink, red, and orange tones.
Ecology
Larvae are generalist feeders on a wide range of deciduous trees. Primary host families include Magnoliaceae (tulip tree, sweet bay magnolia), Rosaceae (wild black cherry), Lauraceae (sassafras), and Oleaceae (ash, lilac). This extreme polyphagy is enabled by genetic adaptations and efficient detoxification of varied plant secondary compounds.
Adults nectar primarily on flowers in the Apocynaceae, Asteraceae, and Fabaceae families, with a preference for pink and red blooms. They are important long-distance pollinators, capable of covering large territories. The dark morph females gain protection from avian predators through Batesian mimicry of the toxic Pipevine Swallowtail. Major predators of larvae include birds, spiders, and parasitoid wasps.
Host Plants
Larvae feed on an exceptionally broad range of deciduous trees. Key hosts in Ontario include:
- Tulip Tree (Liriodendron tulipifera)
- Wild Black Cherry (Prunus serotina)
- Sassafras (Sassafras albidum)
- Ash species (Fraxinus)
- Magnolia (Magnolia acuminata)
- Hoptree (Ptelea trifoliata)
Habitat
The Eastern Tiger Swallowtail occupies a wide range of habitats: deciduous woodlands, forest edges, fields, riversides, roadsides, gardens, and urban parks. In Ontario, it is a common resident of the Carolinian Forest zone and extends northward into the Great Lakes-St. Lawrence forest region. Its adaptability to diverse habitats and host plants contributes to its abundance and secure conservation status.