Notes on the Biology of A “Weedy” Butterfly Pieris Occidentalis (Lepidoptera, Pieridae), at Fairbanks, Alaska

Abstract

Pieris occidentalis is a colonizing species breeding on the weedy cruciferous annual Lepidium densiflorum in the railroad yard at Fairbanks, Alaska. Its behavior and ecology are very similar to those of a railroad yard population previously studied in the Sierra Nevada of California. Despite the high latitude, the Fairbanks population is potentially multivoltine and polyphenic, attributes associated with colonizing ability. Pieris occidentalis and its lowland sibling P. protodice are interpreted as preadapted to disturbed, man-associated environments by their natural dependence on early-successional vegetation.