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WSU/Pend Oreille Extension introduced the Sense of Place series in 1999, with a focus on local landscape and natural history of Pend Oreille County, Washington. A partnership with the Kalispel Tribe of Indians Natural Resources Department has allowed us to expand this program through EPA funding to include more classes, a newsletter and this website.

Butterflies and Bushes

by Carol Mack

Though most folks here are probably unaware of it, Pend Oreille County has a statewide reputation as a butterfly “hotspot.” We sit on the crossroads of the Northern Rockies, Interior Basin, and Canadian Rockies ecosystems. This combination creates habitat for over 100 butterfly species, some that can be found nowhere else in the state. Though birders get more media attention, the sport of butterfly watching is growing by leaps and bounds. Leaping and bounding is often required to net a specimen for a closer look before releasing it. But new field guides emphasizing use of binoculars make it possible to identify the insects without strenuous chases, and are partly responsible for the growing popularity of this pastime.

Recognizing our butterfly richness, the Washington Butterfly Association annual conference is scheduled in Metaline Falls this July, again. (The conference was here in 2003 also.) Both evening classes and field trips during the conference are open to the public--see class insert for information on this and on local “Sense of Place” butterfly field trip opportunities.

Our Pend Oreille butterfly diversity is intimately tied to our native habitat. The study of butterflies inevitably leads to the study of plants. You may see adults sipping nectar from a variety of flowers, but when it comes time to lay eggs, most of our species get very picky. Females sense the chemical makeup of a plant through sensors in their feet, and can recognize the “host plant” they need for their offspring. If the particular host plant for the caterpillars is not around, that kind of butterfly will not reproduce here. A beauty called the Pink-edged Sulfur will only feed on huckleberry brush, the California Tortoiseshell uses our snowbrush, three species are dependent on stinging nettles (Milbert’s Tortoiseshell, the Hoary Anglewing, and the Red Admirable) and the beautiful orange fritillaries nectaring in our flower gardens will only lay their eggs on wild violets. Our hundred kinds of butterflies are here generally because their host plants are still here.

Biologists speculate that this host-specific dependence is a result of co-evolution—a sort of chemical arms race between plant and plant-eater. A plant that happens upon producing a repulsive or poisonous compound has a greater chance of survival, and that character spreads through the species population. The defense may be successful for a while, but eventually a particular grazer adapts to it. The plant ramps up the concentration, and the predator eventually adapts (and may even use the compounds as a defense of its own). But success comes at a cost. The insect becomes dependent on particular plant compounds, needing them to trigger both egg-laying and larval feeding. Many can no longer feed on any other species.

This herbivore pressure on plants has led to wonderful adaptations both medicinal and flavorful. Think of mints, oregano, spicy nasturtium leaves, the smell of pine resin on a sunny afternoon. Most of the aromatic smells, unique tastes and medicinal properties we enjoy in plants came about as a defense. Butterflies are only the visible tip of the iceberg when it comes to the world of insect herbivores driving these botanical experiments. But butterflies are so wonderfully visible—and give us a small window into understanding the amazing connections between plants and insects.

As July unfolds, take a closer look at the butterflies flitting about the yard—and then look beyond the garden, and appreciate the wild trees, shrubs and plants that support these gorgeous bugs.

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