Throughout July and August some of nature’s most colorful creatures bob and float in the garden. A Western tiger swallowtail hovers over zinnias. The tiny white cabbage butterfly zigzags toward daisies. When they were caterpillars in the garden during the months of May and June, we hated them. By August, we’ve forgotten about the destruction; we’re ready to enjoy their company.
In their final egg-laying stage, butterflies dip and dive as decorative blips on the horizon. They’re photographed, cherished by children and beloved in all cultures as symbols of ephemeral beauty. But there’s much more to know about butterflies than only poetic beauty. While they may represent transformation and transcendence, nature has a more pragmatic purpose for them: caterpillars are the main protein on the food chain for wilderness creatures.
They begin as eggs deposited on a specific plant or family of plants. Then each enters a complex series of caterpillar stages. The caterpillar must molt a new skin-like covering with each spurt of growth. It feeds on only a few select plants, called host plants. In-between the molting, the odd stages are referred to as instars. It is throughout the caterpillar period that birds, gardeners and wasps attack the butterfly-to-be. Few survive to the final stage. Finally the caterpillar spins a silken girdle and affixes to a rock or tree in chrysalis form, looking often like a brown leaf dangling from a twig, and waits to emerge as a butterfly.
Butterflies are ancient. Tiny fossil remains have been unearthed at Florissant Fossil Monument west of Colorado Springs. The brush-footed butterfly once haunted the Monument 40 million years ago. And it does so today as a painted lady butterfly. The host plant for the painted lady caterpillar is a collection of thistles, perhaps as prevalent today as millions of years ago. The grassy valley of the Monument provides daisies, penstemons, mariposa lilies and other nectar-rich blossoms for the adult butterfly.
Other prominent ancient plants serve as host plants, too. Aspens and ponderosas, cottonwoods and chokecherry shrubs. The velvety black-and-white Weidemeyer’s admiral chomps on the aspen when it’s a caterpillar. The Western tiger swallowtail chooses a cottonwood or chokecherry. Some butterflies lay eggs on a variety of plants, which assures them many generations to follow. Others, like the monarch, choose only milkweed species. As milkweeds decline in the wild, monarchs decline, too.
Not all butterflies are so endangered, although gardeners may prefer them to be. There’s the scourge of gardeners everywhere: the white cabbage butterfly that chooses a prize cabbage or broccoli as the host plant for eggs. We spy these tiny caterpillars as the green cabbage caterpillar chewing holes in a perfect head of cabbage. This is one of the most successful of all butterflies, covering all of North America and originally hailing from Eurasia.
You might not care to offer up plants from the mustard family to these small green caterpillars. Organic gardeners usually spread row cover over new transplants to keep the adult butterfly from laying eggs on their produce.
But other caterpillars may be tolerated. The parsley worm transforms into the elegant black swallowtail butterfly. They won’t eat much of the parsley, dill or fennel, and you’ll enjoy the sight of black swallowtails throughout the end of the summer. And there are many other butterflies to look for, too, 700 species within North America alone. Skippers and hairstreaks, azures and coppers: they are grouped with colorful names. Gossamer wings, metalmarks, snout butterflies, satyrs—most of the large families often are organized by appearance. Sulphurs are yellow or greenish yellow. Checkered butterflies do sport squared spots. These are among the most flamboyant designs while other butterflies appear modest, draped in brown scales, looking a bit like moths.
It’s not easy to separate butterflies from moths. Both are in the huge genus of Lepidoptera, but moths have a few distinct characteristics. They appear a bit hairier, fly at night, tend to fly slowly in a straight line, spin a silken cocoon rather than hang nakedly as do butterflies in their chrysalis state. The silk moth provides silk from its cocoon. But moths provide something even more important: moths are excellent pollinators. And while the landing pads of daisies appear tailor-made for butterflies, the wide-cupped white flowers that open at night, like the white stemless evening-primrose, are moths evolutionary partners.
Butterflies dip and dart in a zigzag fashion—all the better to avoid predators. Birds consider them less tasty than moths, which allows butterflies to fly in the daytime. And unlike moths, some butterflies are poisonous to birds–the monarch is one example.
While host plants provide camouflage for many moth and butterfly caterpillars, the milkweed host for the monarch provides a poison. The caterpillar feeds on milkweed leaves and the acrid sap introduces a poison into the caterpillar body. No bird will take a chance on eating a butterfly they believe to be deadly.
If you set out for a butterfly hike, you’ll find butterflies throughout the months of July and August in the narrow bands of altitude where they flourish. Alpine butterflies won’t be found below a certain altitude and the eastern plains butterflies exist only on the prairie. In the foothills, butterflies may be of greater diversity simply because the sudden rises in altitude creates bands of habitat within an hour of hiking.
Choose a sunny meadow with a variety of wildflowers. Or plant a garden filled with flowering plants—especially native plants or plants with considerable nectar, like zinnias. The more blooms you offer, the more butterflies will arrive. Enjoy each one because many butterflies indicate nature’s diversity is intact–so far.
Butterflies are linchpins in the natural world. They are a major food for other insects and birds. As they disappear, that critical food source disappears, too. Sometimes they are felled by extended drought, habitat changes or unusual diseases. So if you have a garden, consider giving them a break from pesticides, lend them a helping hand with host plants and flowers. Best of all, enjoy their colorful beauty when August arrives.