The Eastern Tiger Swallowtail is far less common in Vermont than the Canadian Tiger Swallowtail, yet equally striking in appearance. It was probably the first North American butterfly to be described and drawn by Europeans in the New World. Like the Canadian Tiger Swallowtail, this butterfly is an adaptive generalist, but is apparently not as tolerant to cold climates. There are black form females caused by a gene that produces melanism and is most common in areas where the distasteful Pipevine Swallowtail populations are highest, perhaps conferring it with protection from predation. Males patrol for receptive females. Females lay eggs singly on host leaves. Caterpillars rest on silk mats in shelters of curled leaves. Overwinter in chrysalis.
Male is yellow with dark tiger stripes. Female has 2 forms: one yellow like the male and the other black with shadows of dark stripes. Hindwing of both female forms has many iridescent blue scales and an orange marginal spot. On the underside of forewing of both female forms the row of marginal spots has merged into a continuous band.
Resident – uncommon
Two generations, the first eclosing in May and the second at the end of July. Extreme dates: a dark form female on 27 May 2006 in Pownal (K. Hemeon), 6 individuals in Castleton (R. Pilcher) and 4 in Orange (A. Aversa) on 25 August 2005, 19 September 2000 in Burlington (B. Waldron).
Distribution and Habitat
North American range- Eastern North America from Ontario south to Gulf coast, west to Colorado plains and central Texas.
Not a common butterfly in Vermont and even less so in the north. A curious distribution in Vermont, with records in the southern tier expected, but the cluster of records from central Vermont is difficult to explain. A similar pattern emerges from the few historical records too.
They can be found in deciduous broadleaf woods, forest edges, river valleys, parks, and suburbs. Caterpillars feed on Birch (Betula), Ash (Fraxinus), Cottonwood (Populus), and willow (Salix). Adults nectar from a wide variety of flowering plants.