The Old World Swallowtail (Papilio machaon) is also known as the "Common Swallowtail" since its range is large, from Europe into North Africa and west across northern Asia and North America.
It is frequently encountered at altitudes as great as 15,000 ft. In the United States it is only found west of the high plains, where it is best observed in mountain meadows.
The butterfly has yellow wings with black vein markings and a pair of protruding tails. Just below each tail is one red and six blue eye spots.
The Old World Swallowtail caterpillar spends the first part of its life with the appearance of a bird dropping as a defense mechanism against predators. As the caterpillar grows larger, it becomes green with black and orange markings.
The food plants it uses cover a wide spectrum in different geographic areas: wild carrot, wild angelica, fennel, rue and hogweed.
Wing spread: 2 1/2" - 3"
The similar Oregon Swallowtail (Papilio oregonius or Papilio machaon oregonius) is found only in Oregon, Washington, Idaho, and south-central British Columbia. This butterfly lives east of the Cascades below 4,000 feet elevation in sagebrush-dominated canyons, plateaus and mountains throughout the Columbia and Snake River basins.
Oregon Swallowtails have wingspans up to 4-inches that have a bright yellow with black-lined pattern and a tail that extends off the back wing. The yellow wing markings of the Oregon Swallowtail are brighter than the similar Old World Swallowtail. It is also similar in some respects to the Anise Swallowtail and the Indra Swallowtail.
The caterpillar is black with yellow markings.
It was declared the official insect of the State of Oregon in 1979.
Old World Swallowtail Butterfly (dorsal view)
Old World Swallowtail Caterpillar