3-3 3/4" (76-95 mm). Pale cream with bold, broad black stripes and black borders above; HW borders spotted with cream, blue, and pale to bright orange. Wings less brightly colored below, with distinctive dark veins. 1 long black tail on each HW.
Western Tiger Swallowtail lemon-yellow, has paler veins below, and narrower black bands. Two-tailed Tiger Swallowtail has more tails, narrower black bands, and is deeper yellow.
Egg chartreuse. Caterpillar, to 1 3/4" (44 mm), soft green with yellow and black eyespot patterns. Chrysalis barklike, dark brown
streaked with black. Preferred host plants
mostly in buckthorn family, including mountain lilac and mountain balm (Ceanothus), also holly-leaf cherry (Prunus ilicifolia) and coffeeberry (Rhamnus californicus) in California, and alders (Alnus).
1 brood; late spring-midsummer, varying with latitude and altitude.
Mountainous or hilly country with broadleaf scrub or chaparral, dry slopes, canyons, and roads; ocean bluffs in Northwest, sea level to timberline.
British Columbia and Montana south to New Mexico and Baja California; and in Cascades, Sierra Nevada, Coast Ranges, and Rockies. Absent from drier, hotter parts of basins and deserts.
Less numerous than other tigers, the Pale Tiger Swallowtail occurs widely throughout the West. It tends to fly rapidly in complex patterns between buckthorn bushes. Unlike its yellow relatives, it does not course up and down canyons all day but rather seeks hilltops. It takes nectar from mints, thistles, and buckeyes. Males settle more often on damp earth, sometimes in great congregations