Butterflies on San Bruno Mountain

The Pipevine Swallowtail or Blue Swallowtail (Battus philenor) is a swallowtail butterfly found in North America and Central America. The butterflies are black with iridescent blue hind wings. They are found in many different habitats, but are most commonly found in forests. The black or red caterpillars feed on Aristolochia species, making them poisonous as both larvae and adults, while the adults feed on the nectar of a variety of flowers. less ↑

Battus philenor hirsuta, the California pipevine swallowtail, or hairy pipevine swallowtail, is a subspecies of the pipevine swallowtail that is endemic to Northern California. Populations are found throughout the Sacramento Valley and outside of the valley in Contra Costa and Alameda Counties. The butterfly is black with hind wings that have iridescent green-blue coloring above and a row of red spots below; the caterpillars are black with fleshy protrusions and red spots. The subspecies' butteflies are... less ↑