Swallowtails belong to the worldwide family Papilionidae. When Linnaeus coined the name Papilionidae in 1758 this was one of the first butterfly families, and as such it included most of the world’s species of butterflies. Today, while the family is much more restricted, it still includes some of the world’s most spectacular butterflies. All seven of Washington’s swallowtail species are included in the genus Papilio. Swallowtails are large to very large, brightly-colored butterflies, with many but not all species bearing rear wing extensions resembling “tails”. Swallowtails are elegant butterflies, flying powerfully but seemingly effortlessly with not very rapid wingbeats, often interspersed with long glides. The Two-tailed Swallowtail is Washington’s largest butterfly.

Papilio multicaudatus occurs throughout much of western North America, from southern Canada south through the Dakotas to Texas, Mexico and the northern parts of Central America. Within Washington State it is found east of the Cascade Mountains, but not on the west side. This superb large butterfly is often found cruising open canyons at low and mid elevations on the east flanks of the Cascades. All of Washington’s swallowtails overwinter in the chrysalis stage, emerging in the spring to feed and mate. Adults have been reported on the wing in Washington from mid April through August. Females lay large white spherical eggs singly, near the center of the dorsal (top) side of host plant leaves, usually in a shaded area out of the direct sun. The females can be observed alighting on host plant leaves, carefully examining them, then flying on to other leaves, before finally depositing one single egg per shrub. Interestingly, eggs are often placed on partially eaten or damaged leaves even though more perfect leaves are available nearby. The adult then flies, often a substantial distance, to another shrub and repeats the process. On hatching, the larva feeds on the host plant, eating holes clear through the tender tip-most leaves. It constructs a thin silk mat on the dorsal side of a leaf where it returns to rest when not feeding. The larva is green and very large, reaching a size greater than 60 mm, and bearing big false eyespots to confuse predators. Near the head there is a concealed, foul-smelling bright orange osmeterium which can suddenly be everted out to further deter predators when the caterpillar is disturbed. The chrysalis is brown and cryptic, attached at the base and angling upward, and secured at the middle with a silk girdle. In captivity about 5 weeks elapsed from egg to pupation.

Four of Washington’s swallowtails are of the “tiger” type, with wings of a light background color and with several contrasting black stripes extending from the leading edge of the forewing, slightly tapering backward and angling inward toward the body. In the Two- tailed Swallowtail the ground color is bright lemon yellow.

The Two-tailed can be distinguished from its smaller tiger cousins by its larger size, brighter lemon yellow color, narrower black tiger stripes, and distinct flight pattern with more gliding than the other species. Additionally, as its name suggests, the Two-tailed.

All photos by Dave Nunnallee

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