Viceroy

Orange-and-black brushfoot butterfly whose larvae feed on trees in the willow family (Salicaceae) - willows (Salix) plus poplars, aspens, and cottonwoods (Populus). Caterpillars sequester salicylic-acid compounds from these hosts, which makes the adults distasteful to birds; the viceroy and the monarch are now understood as Müllerian co-mimics, two unpalatable species that share a warning pattern and reinforce each other's protection rather than the long-taught one-way Batesian story. Larvae overwinter as third-instar caterpillars inside a rolled-leaf hibernaculum anchored to a host twig, so leaving willow and poplar leaf litter and standing stems undisturbed through winter directly protects the next generation.

Larval host plants · 5

Across most of North America east of the Cascade and Sierra Nevada ranges, from southern Canada (north to the Northwest Territories) through the eastern and central United States to central Mexico and Florida; largely absent from the far Southwest and parts of the Pacific coast.