May 30th, 2010


50 More Urban Species #13 Red Admiral, #14 Eastern Tiger Swallowtail

Red Admiral Vanessa atalanta

The red admiral is an attractive medium sized butterfly with an extremely widespread distribution, found in almost the entire northern hemisphere from the subarctic to the subtropics. It's a member of the "ladies" in Genus Vanessa including the American lady and painted lady butterflies. In Boston red admirals may overwinter as adults if the winter is not too severe, or they may migrate from further south. The larva lives on plants in the nettles family, including urban weeds like stinging nettles and clearweed. The individual pictured was one of a several red admirals that were dividing their time between sunning themselves for temperature regulation and engaging in frantic territorial behavior.

Eastern Tiger Swallowtail Papilio glaucus

This is one of several tiger swallowtail species found in North America. They are all large yellow butterflies, though females of the Eastern species also come in midnight blue and black. The larva can survive on the leaves of many different shrubs and trees, including commonly seen urban plants like birches, willows, and tulip trees. While feeding, the young caterpillars are protected from predacious birds by their cunning camouflage: they look like bird droppings. As they get older and larger, the caterpillars turn green and develop eyespots, and even display snake mimicry behavior to defend themselves. There may be several generations per year, but the last to pupate in the fall will tuck into a leaf and remain in the chrysalis for the winter.