Oregon Symbols, Insect: Oregon Swallowtail Butterfly

Adopted in July 16, 1979.

In 1979 the Legislature designated the Oregon Swallowtail as Oregon's official insect. A true native of the Northwest, the Oregon Swallowtail is at home in the lower sagebrush canyons of the Columbia River and its tributaries, including the Snake River drainage. This strikingly beautiful butterfly, predominantly yellow, is a wary, strong flier not easily captured.

 On June 6, 1977, the U.S. Postal Service issued a set of four stamps illustrating American butterflies. One stamp depicted the Oregon swallowtail. But the greatest honor came on July 16, 1979, when the Oregon swallowtail was adopted as Oregon's state insect.

There is probably no other family of butterflies as familiar to everyone as the Swallowtails. This family includes many of the largest and most beautifully colored American butterflies. Most of the five hundred species of Swallowtails are found in the tropics and the Birdwing Swallowtails, from tropical Australia, are among the biggest butterflies in the world.

There are two notable differences between Papilio oregonius and the common Swallowtail, Papilio machaon. The eye-like spot on the front of each wing, about 3mm in diameter on the P. machaon, is reduced to almost a dot on the P. oregonius; the bright yellow bands parallel to the thorax, crossing the wing bases on the P. oregonius, are much duller on the thorax of P. machaon. The Papilio oregonius is probably a descendant of varieties found in South America. Its establishment in the Pacific Northwest was aided by the warming produced by the California current which is unusual at latitudes that high. The Oregon Swallowtail reproduces twice a year, and can be seen on the wing from April to September in the Northwest. Those seen early in the year are generally lighter in color than those seen later and blend well with the color of early plants. The distribution of Papilio oregonius is from southern British Columbia, eastern Washington and Oregon, to Idaho and western Montana.

Wing span: 2 1/2 - 3 inches (6.5 - 7.5 cm).

Identification: Upperside of hindwing near tail has reddish-orange eyespot with black along lower border. Edge of hindwing and body are hairy.

Life history: Females lay eggs singly on the host plant, and newly-hatched caterpillars eat the leaves. Older caterpillars feeding on plants of the parsley family prefer to eat the flowers. Chrysalids overwinter.

Flight: In north, one flight in late May-July; two flights in south.

Caterpillar hosts: Arctic sagebrush (Artemisia arctica) in the sunflower family (Asteraceae), and some species in the parsley family (Apiaceae).

Adult food: Flower nectar.

Habitat: Open hilltops, mountain meadows, tundra.

Range: Holarctic. In North America, south from Alaska to northern British Colombia, east across Canada. Southern British Colombia south through New Mexico.

Comments: Includes P. brevicauda, P. joanae, P. oregonius and P. bairdii.