Description 1 7/8-2 3/8" Wing margins
ragged. Above, rich russet with black
blotches on FW, small white spots on FW
costa, black and white pair of spots on HW
costa, margin dark often with hint of blue.
Below, dull barklike brown, lighter outwardly,
contrasting with darker base; margin lined
with deep blue marks. FW tailing edge
Life Cycle Caterpillar velvety black with
yellow and blue-black spines and white
specks. Chrysalis gray and tan, may have
blue cast; horned head. Various buckthorns
(Ceanothus) are host plants; probably also
Flight 1 brood in North, 2 or 3 farther south;
adults may be encountered year-round.
Habitat Mountainous terrain below
subalpine zone, especially canyons; also
lowland forest edges, glades, and parklands.
Range British Columbia south to S.
California, and east in mountains to
Saskatchewan, Nebraska, and New Mexico;
very rarely wandering or introduced into
Midwest and Northeast.
Discussion The California Tortoiseshell
may be rare or absent from large parts of its
range for several years. These dearths are
followed by periods of enormous abundance,
involving emigrations over immense areas,
which seem to be related to population
pressures, host plant availability, and climate