Butterflies and Moths
Butterflies found in the Pacific Northwest include Spicebush Swallowtail, Painted Lady, Cabbage White and Red Admiral. Migratory Monarch butterflies are found throughout most of the United States. They migrate north in the spring and can be found in Washington State, mainly east of the Cascades where milkweed is abundant. The Washington Butterfly Association publishes a list of butterflies found in the Puget Sound Region and their food plants.
The beauty of butterflies can make us overlook moths, which are much more plentiful than butterflies (and sometimes just as pretty). Moths and butterflies are part of the group Lepidoptera, which means “scaly-winged.” During the day, we encounter many more months than butterflies. There are about 1200 moth species in the Pacific Northwest compared to approximately 149 species of butterflies. Moths are mostly nocturnal and are busy pollinating at night when other bugs are asleep.
Butterflies and moths are important pollinators but their populations are in decline, mainly due to habitat loss. Butterflies and caterpillars are also important food sources for other pollinators, such as birds. The Xerces Society (named for the now extinct California butterfly Xerces Blue) provides education and guidance on butterfly conservation worldwide.
Caterpillars
Caterpillars are captivating little critters. They provide food for birds, spiders and parasitic wasps. And through the incredible change called metamorphosis, they become butterflies and moths.
Moths and butterflies lay eggs on the leaves of a caterpillar’s host plant, which is also its source of food. The eggs hatch into caterpillars, which grow at an incredible rate, feeding constantly. During this growth, they shed their skin multiple times. Metamorphosis begins when a caterpillar is fully grown, at which point a butterfly forms a protective chrysalis and a moth spins a silk cocoon. When metamorphosis is complete, a butterfly or moth emerges to begin the life cycle all over.
Caterpillars native to the Pacific Northwest include the Tent Caterpillar species and the native Swallowtail and Admirals species. They feed on host plants such as Bitter Cherry, Willow and deciduous trees.