Category: Instars

Spicebush Swallowtail Caterpillar

Several days ago I wrote about the adult Spicebush Swallowtail (Papilio troilus). The caterpillar of that beautiful butterfly has an impressive set of eyespots giving the caterpillar the look of a small snake which protects it from predators. The actual eyes are quite small, about the size of a pinpoint, located down the head, close to the mouth.

The Spicebush Swallowtail goes through five instars, or caterpillar stages, taking three to four weeks. In the first four of those instars the caterpillar looks much like bird poop with small false eyespots that get larger as each instar emerges. Like those eyespots, the bird poop camouflage works well as a protection against predators.

An element on the eyespot really impresses me. There is a white spot on the black pupil, a faux reflection! As the fifth instar ages, it goes from bright green to rich sunshine yellow leaning toward orange. Once the Spicebush Swallowtail reaches the adult and butterfly stage, it lives for just six to fourteen days nectaring on many flowers including jewelweed, milkweed, and thistle.

Blackhaw Viburnum

A large bush that I’ve been delighted to find is Blackhaw Viburnum (Viburnum prunifolium). It’s growing by my backdoor, and there’s lots of it growing in the woods all around my cabin.

The leaves of Blackhaw emerge from the buds involute, or curled as a spiral. The mature, glossy, opposite leaves are three to four inches long and one inch wide with fine serrations and pointed at the end. The petioles, or stems, of the leaves are a reddish color. In the autumn the leaves turn a purply-red.

Soon my bush will have buds. Buds that will become clusters of fragrant flowers four to five inches across. Flowers that will attract bees and flies to do their pollination magic.

Blackhaw Viburnum is the host plant of Spring and Summer Azure butterflies. The later caterpillar instars of the Baltimore Checkerspot butterfly occasionally feed on its leaves. Oh I wish I’d see a Baltimore Checkerspot butterfly! I’ve seen their caterpillars while pulling invasives in Shenandoah National Park. Never the adult though.

Its fruits, called drupes, are about one half inch long. They’re eaten by songbirds, gamebirds, squirrels and chipmunks.

As a tree Blackhaw Viburnum can grow to be thirty feet tall. Its bark blocky in a Persimmon tree sort of way. Large bush, small tree, all in all a mighty cool plant.