Did you ever see a caterpillar and wonder what it was going to be later? There are about 11,000 species (in North America, not including Mexico) divided into 80 families of caterpillars. That’s quite a few to try and recognize. So we’ll start with a few of my favorites.
Before we begin, here’s a general description of the caterpillar. They will generally fall into one of these categories: smooth, smooth with knobs and bumps, smooth with a rear tail, smooth with fleshy filaments, slug-like, hairy, hairy with tufts, bristled, branched spines or internal feeders, which eat the inside of a plant but not the leaves.
Let’s start with the one everybody knows, the woolly bear. This is the fuzzy one that’s red in the middle and black on the ends, about 2¼ inches long, that you see crawling across the driveway or road. It is said the width of its band foretells the severity of the winter. Sorry — the color is based on other factors, such as its age. At each molt, the black is replaced by red. This caterpillar eats dandelions and other low-growing weeds. Why it travels the way it does is still a mystery. It becomes an Isabella tiger moth.
One caterpillar recognized almost as much is the monarch caterpillar. It gets about 2¾ inches long and is found on milkweed leaves, where it absorbs the toxins making it nasty-tasting for birds. It is white with yellow and black stripes, with long black filaments at the head and shorter ones at the tail (so you can tell which end is which). These guys can go through their life cycle in as little as 30 days. These are excellent for the classroom as the transformation is visible within the chrysalis. One day before it emerges, you can see the colors of the butterfly.
The Luna Moth caterpillar gets about 2¾ inches long and is a smooth light green with a light yellow line along each side. It also has many red or orange short round knobs. It prefers to eat hickory leaves but will feed on other trees such as willow, maple, oak and beech. This is a large moth with a wing span of up to five inches, most often seen in late spring or early summer. The wing edge color varies according to the season; spring moths have a pinkish-purple edge to their wings, while the summer ones have a yellow edge.
The caterpillars that become zebra swallowtails will get up to two inches long and are green with a bold black band and many yellow ones crossing their backs. They prefer Pawpaw plants and are found mostly in wet areas such as marshes, swamps and wooded riversides. They can be cannibalistic if need be. Their adult wing span is around three inches.
Then we have the pipevine swallowtail. This fellow gets about two inches long and is purplish-black with blackish red fleshy filaments. The first segments of the caterpillar have large filaments that look almost like pincers. This butterfly gets a wingspan of about 4½ inches.
Another large moth around here is the Promethea moth. Its caterpillar gets about three inches long. It is mostly smooth and bluish-green with different colored knobs. You can find it mostly on wild cherry trees or spice bushes, but it also enjoys maple, apple, ash, tulip, sweetgum and sassafras. The females are larger than the male, have a wingspan of up to six inches and are more colorful.
The yellow bear caterpillar is sometimes confused with the Woolly Bear. Although at first glance they look the same, if you look closely, you can see the segments it has. It is a very hairy caterpillar, up to two inches long, and it can be beige, yellow, dark red-brown, orange or almost black. It will feed on birch and maple trees, on cabbage and corn or on many other garden crops. This guy becomes the Virginian tiger moth.
Joe Whitfield is a naturalist and gardener for the Greenfield Parks and Recreation Department. Send comments to firstname.lastname@example.org.