Bring on the butterflies

Sunset, March, 1998 by Sharon Cohoon

It's no secret. The key to a wildly successful butterfly garden is providing lots of caterpillar food. Period.

Sure, if you have nectar plants in your garden, adult butterflies flitting through the neighborhood will drop in for a quick drink. But if you don't have food to offer future progeny, the butterflies won't stay. A quick sugar fix and the females are gone, continuing their search for the specific plants they depend on to nourish their caterpillar offspring. And where there are no females, males don't linger.

If, on the other hand, you also have plants in your garden that caterpillars can feed on, the females will stay to lay their eggs. And you've got a front-row seat for the butterfly's remarkable rite of passage from egg to caterpillar to chrysalis to winged adult. Witness this metamorphosis a few times, gardeners attest, and you'll start thinking of yourself as a butterfly grower rather than a gardener; of caterpillars as endangered species rather than threats to your plants; and of defoliated plants as a lepidopteran triumph rather than a horticultural defeat.

Adding host plants for caterpillars definitely increases the total number of butterflies in your garden. And, as Louise Hallberg discovered when she retired and took up butterfly gardening, it can add to the variety of butterflies there as well. Hallberg was used to seeing pipevine swallowtails on her property in Sebastopol, California. Back in the '20s, her mother had planted California Dutchman's pipe, their caterpillar food plant, and the vine had slowly multiplied, covering fences and scrambling up trees and luring in hundreds of egg-bearing pipevine swallowtails each spring. But monarchs are new to Hallberg's garden. They didn't arrive until she planted milkweed a few years ago. By letting weedy dock and sorrel return to her pasture, she has recently attracted purplish coppers. And she's hoping the addition of some canyon live oaks this year will bring back California sisters.

Adding caterpillar plants to our gardens not only lures butterflies but also helps them, says Jeff Glassberg, president of the North American Butterfly Association (NABA), a nonprofit organization that promotes public awareness and conservation of butterflies. It extends their shrinking habitat and can even bring a species back from the brink. The atala, a beautiful metallic blue hairstreak butterfly, is a good example, says Glassberg. Once common in Florida, then believed to be extinct, the species has staged a comeback. The cycad, its host plant, has become a popular landscaping specimen in the state, so now there's plenty of atala caterpillar food to go around.

FROM FEAR & LOATHING TO FOSTER PARENTING

Since caterpillar plants are the best way to attract butterflies, why are gardeners so reluctant to add them to their gardens? They confuse voracious with omnivorous, says Mark Dimmitt, associate director of science for the Arizona-Sonora Desert Museum. They watch gulf fritillary caterpillars vigorously chomping away at passion vines and think they're going to denude the entire garden.

But caterpillars are actually quite picky eaters. Species like cabbage whites that feed on many plants - anything in the brassica family - are rare, Dimmitt says. Most caterpillars have evolved to depend on only one or two host plants and eat nothing else. The blame for nibbles out of your other plants belongs elsewhere, he says.

Gardeners also don't realize how many natural predators caterpillars have, says San Francisco butterfly enthusiast Barbara Deutsch. Birds pick them off by the score. Spiders, wasps, mantids, lizards, and rodents eat them. And parasites finish off most of the rest. In fact, says Deutsch, the odds against any single caterpillar making it to winged adulthood are slim. Once they learn this, butterfly gardeners often feel compelled to intercede. They start rescuing eggs and rearing caterpillars and releasing adults to improve the butterfly population's long-term chances. "You start out thinking caterpillars are going to eat up all your plants," she says, "but you end up wishing for caterpillars."

GETTING TO KNOW BUTTERFLIES

The following tools can help you get to know butterflies.

A good identification book - National Audubon Society Field Guide to North American Butterflies or A Field Guide to Western Butterflies (from the Petersen field guide series), for instance - is essential.

A pair of binoculars brings the exquisite detail in butterflies' wings into close focus. NABA's Glassberg recommends a pair at least 7X power that focuses to less than 6 feet. For a reprint of his binocular product review, send a self-addressed, stamped envelope to NABA, 4 Delaware Rd., Morristown, NJ 07960.

The Butterfly Book: An Easy Guide to Butterfly Gardening, Identification, and Behavior, by Donald and Lillian Stokes and Ernest Williams (Little, Brown and Company, Boston, 1991; $12.95), is still one of the best primers on butterfly gardening on the market. Butterfly Gardeners' Quarterly (Box 30931, Seattle, WA 98103) is also well worth its $8 annual cost.