Lepidoptera: Papilionidae: Papilio rutulus Lucas, 1852 (Western Tiger Swallowtail)

This large species (its wings span up to 4 in., or 10 cm), with its brilliant yellow wings crossed by black stripes, is one of our most conspicuous butterflies. Although more prevalent in riparian situations in rural and wild areas, it is not uncommon in urban and suburban residential districts.

Photograph by C. Hogue

The mature caterpillars are all green except for two "eye" spots on the back of the swollen thorax and a transverse black-margined yellow band a short distance behind the eye spots on the tapering abdomen; there are small lavender spots on each segment. The principal local food plants for the larvae are poplar, willow, sycamore, and alder (Alnus species). The chrysalis of the Western Tiger and other swallowtail butterflies rests in an upright position against a tree trunk or other vertical structure. It is attached at the bottom or tail end by a button of silk and is supported by a thread-like girdle around the middle, an arrangement that suggests a window washer standing on a building ledge and leaning back on his safety belt.

© 1993 Insects of the Los Angeles Basin