If No Caterpillars, Then No Butterflies

The U.S. Secretary of Agriculture has proclaimed June 17-23, 2013 as national Pollinator Week. According to http://www.pollinator.org Pollinator Week has grown to be an international celebration of the valuable ecosystem services provided by bees, birds, butterflies, bats and beetles.

In honor of Pollinator Week, let’s talk about those lovely flying pollinators-butterflies. The Conservatory of Flowers in San Francisco’s Golden Gate Park is showcasing “Butterflies and Blooms” through October 20. If you’re visiting the Bay Area, stop by to see up to twenty species of North American butterflies, including monarchs, admirals and western swallowtails, some just emerging from their chrysalis. How can it be that the crawly, worm-like creature-a caterpillar-can create that chrysalis and then turn into a graceful, soaring butterfly?

Start with a good butterfly book with pictures of butterfly larvae and identify the caterpillars in your garden. Put away your pesticides! Even Bt (Bacillus thuringiensis), recommended for caterpillar control, will kill butterfly larvae. If no caterpillars, then no butterflies.

Watch the butterflies in your garden. When you see one flitting restlessly from flower to flower, you may be looking at a female searching for just the right plants for laying her eggs. Some butterflies lay their eggs in clusters, some singly. The tiny eggs may be round, oval, ribbed, green, orange, or opalescent, but all are laid on plants the mother butterfly believes will be a suitable munching haven for her voracious caterpillar offspring.

The caterpillar’s preferred food is called its “host plant” or “larval plant.” It is well known that the larvae of the beautiful pipevine swallowtail eat only leaves of the California pipevine (Aristolochia californica). Offspring of the elegant monarch will eat only milkweeds (Asclepias). California monarch larvae prefer California native milkweeds, especially narrowleaf (Asclepias fasicularis), purple (A. cordifolia), and showy (A. speciosa). Host plants are frequently natives such as oaks, California lilac, buckeye, violets, penstemon, pines, monkey flowers, thistles, grasses, and of course, the milkweeds and pipevine. Without appropriate food, the caterpillars die. No caterpillars, no butterflies!

Most adult butterflies will feed on nearly any flower that offers both nectar and a broad platform of blossoms on which to alight. Common garden plants include butterfly bush, marigolds, zinnias, asters, daisies, yarrow, and verbena. Butterflies prefer a cluster rather than single plants in an open sunny area; a shallow source of water may also be appreciated.

Vera Strader is a Tuolumne County Master Gardener who uses very few pesticides. Her Sonora area garden is certified as a National Wildlife Habitat garden.