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Earlier this summer, my husband and I were walking near our home. I stopped short to avoid stepping on a bright green caterpillar. It had some modest yellow splotches, but the most conspicuous markings were two large spots that looked like baby eyes on a rounded head. I was delighted to recognize a spicebush swallowtail caterpillar. The butterfly it will turn into is mostly black, sports a trim of blueish green and white spots, and has a wingspan of three to four inches.

The caterpillar itself belongs on a roster of nature’s most adorable babies. If you haven’t seen one in person, look up a picture. Its eye-like spots aren’t eyes at all, however. They’re just a camouflage, a defense mechanism to make hungry birds think it is a much bigger monster, not a tasty morsel.

Caterpillars represent the larval stage of butterflies and moths. The female insect lays an egg, or a bunch of eggs, in a place near an appropriate food source. For example, those lovely leaves in your garden. A week or two after the eggs are deposited, caterpillars emerge. 

They are born hungry. This aspect of caterpillar nature was made famous in the children’s picture book The Very Hungry Caterpillar by Eric Carle. Carle’s caterpillar eats a variety of things like fruit, cake, ice cream, and a lollipop. Regular caterpillars typically stick to leaves and other plant material, and they do eat a lot. 

Some caterpillars are picky eaters. Many plants produce specific chemicals that make them taste bad or cause them to be toxic, so the specific caterpillars that can eat them are the ones that are adapted to the plants’ chemical defenses. Perhaps the most famous picky eater is the monarch caterpillar, which relies on milkweed plants. Monarchs aren’t harmed by milkweed toxins, and the ingested compounds help protect the caterpillars and the adult butterflies they will become from being eaten.

Although caterpillars eat a lot, they are also eaten a lot. Caterpillars supply vital nutrients to a wide variety of wildlife. Diners include frogs, toads, lizards, and some varieties of beetles, wasps, and spiders. But, the most common consumers of caterpillars are birds. Robins, chickadees, wrens, bluebirds, cardinals, and woodpeckers are just a few examples of the many that love caterpillars, and caterpillars are especially nutritious for feathered babies. 

In their book The Living Landscape, authors Rick Darke and Doug Tallamy note that 96% of terrestrial birds in North America feed insects to their young. Quite often the preferred form of insect is the caterpillar. In the case of chickadees, they note that caterpillars comprise 95% to 100% of food fed to young. “Because chickadees rear their young exclusively on caterpillars, there will be no chickadees where there are no caterpillars,” they note. 

The number of caterpillars required is more than you might think. Tallamy and Darke say that, depending on clutch size, Carolina chickadees bring their young between 390 and 570 caterpillars every day from the time they hatch to a few days after they fledge, usually a couple of weeks. That totals 6,240 to 10,260 caterpillars for one brood of a relatively small bird. When you consider the vast array of birds with similar menu preferences, you end up requiring a staggering number of caterpillars.

Caterpillars that escape being eaten move into the next stage of their lives. A butterfly will form a chrysalis. A moth forms a cocoon. Housed inside these protective environments, they undergo complete metamorphosis. The caterpillar’s cells break down and reorganize themselves to create wings, legs, and other body parts. At the end of the process an adult butterfly or moth emerges. The insects seek out mates, and the cycle continues.

In a healthy environment, plants, caterpillars, birds, and other predators all work together to ensure their mutual survival. According to Tallamy and Darke, stability within an ecosystem is directly linked to its diversity and the presence of native plants and animals that have developed in mutual relationships. This is underscored by studies reporting that native plants support thirteen times more caterpillar species than do imported ones. The balance of nature is as delicate and as beautiful as a butterfly wing.

Karen Bellenir has been writing for The Farmville Herald since 2009. Her book, Happy to Be Here: A Transplant Takes Root in Farmville, Virginia features a compilation of her columns. It is available from PierPress.com. You can contact Karen at kbellenir@PierPress.com.