Western Tiger Swallowtail Butterfly

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Butterflies, Pacific Northwest

Western Tiger Swallowtail Butterfly
Western Tiger Swallowtail Butterfly, Photo By Bud Logan

The western tiger swallowtail is a butterfly that roams the Pacific Northwest including all of the BC coast. The western tiger swallowtail is a member of the family papilionidae, which consists of other subspecies of swallowtail butterflies.

The western tiger swallowtail has a wingspan that is up to 10 cm. The butterfly is bright yellow with four distinct black striped markings mainly on its upper wings. The wings are edged in black and the longest black stripes on the butterfly are on the inner parts of the wings nearest to the insect’s body. Western tiger swallowtails have long tails on their hind wings that resemble the tails of swallow birds. The hind wings also have small patches of blue and a spot or two of orange on them.

Western Tiger Swallowtail Caterpillar
Western Tiger Swallowtail Butterfly Caterpillar, Photo By Robert Logan

A western tiger swallowtail begins its life in a green egg. When the egg hatches, a caterpillar emerges that has a body covered in rows of blue dots with four yellow dots near its head. The caterpillar’s neck has stripes of black and yellow on it. The caterpillar is green in color, but later turns brown before the pupal or chrysalis stage, which is an intermediary stage between the caterpillar and adult butterfly stages. In the pupal stage, the caterpillar, now called a pupa or chrysalis, forms a cocoon and abstains from food or drink. In the cocoon, the pupa or chrysalis undergoes a physical metamorphosis to become a butterfly. In the last stage of development, an adult western tiger swallowtail emerges from the cocoon with wings. It takes about a month for the butterfly to move from the egg stage to the adult stage.

When the western tiger swallowtail is a caterpillar it eats leaves from trees and shrubs, such as willow, alder, bitter cherry, cottonwood, poplar and trembling aspen. As an adult butterfly, the western tiger drinks nectar from a variety of flowers.
The western tiger swallowtail has a wide range of distribution on the west coast of North America.

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