Seattle - Woodland Park Zoo staff is behind the scenes diligently nurturing rare Oregon silverspot butterfly larvae in hopes of stabilizing the species’ population, in grave decline, on the Oregon Coast. The larvae are part of the Oregon Silverspot Butterfly Project, a cooperative conservation program to headstart the threatened butterflies and bring the insects back from the brink of extinction.

Woodland Park Zoo entomologists work on the recovery project in partnership with The Nature Conservancy, U.S. Fish & Wildlife Service, Oregon Zoo and Oregon Natural Heritage Program.

The silverspot was declared a federally threatened species on July 2, 1980. Although its native range spreads from Washington state down to northern California, its populations are small and isolated within its grassland habitats. When a census of wild silverspots was conducted in 2000, only 80 of the orange and black butterflies were seen. Another factor that severely restricts its population is that it relies on a single species of plant for its survival: the early blue or dog violet. The beautiful little violet, once prevalent on Washington's Long Beach peninsula and other places, is now disappearing as habitat is gobbled up by development.

In 1999, the U.S. Fish & Wildlife Service revised a recovery plan for the silverspot and, in partnership with Oregon Zoo and Lewis and Clark College, began a captive-rearing and release program at Rock Creek and Cascade Head in Oregon, sites where patches of violets remain abundant. Both Woodland Park Zoo and Oregon Zoo are directly aiding the effort by headstarting the butterflies, a process similar in some ways to WPZ's long-standing western pond turtle headstart program, which hatches and raises the young in zoos until they reach a size large enough to escape predation in the wild.

The butterfly captive rearing program serves as a stopgap measure to keep the silverspot population stable until its habitat is restored. The Nature Conservancy, working collaboratively with U.S. Forest Service, is currently restoring the native butterfly habitat through small, controlled forest fires. Scientists hope that by bringing back the western blue violet, which silverspot caterpillars depend on for food, the butterfly population can return to its historic numbers and ranges.

This year, nine female butterflies were brought to Woodland Park Zoo from Cascade Head and Rock Creek and were induced to lay eggs in a laboratory. These butterflies were captured toward the end of their life cycle, with the intent they already bred and laid eggs in the field before being brought to the zoo. Every day, butterflies are fed nectar, a solution of sugar, water and egg whites, on saturated cotton balls.

To date, approximately 1,500 eggs have been laid at Woodland Park and nearly 600 have hatched. Each hatched larva is about two millimeters long and, under a microscope, appears to be a perfect miniature caterpillar. At this stage, the larvae do not eat, but are given drinks of water, after which they are placed in specially designed containers, and put into a refrigerator for winter diapause, or, hibernation. After winter dormancy, the butterfly larvae will feed on western blue violet leaves until they pupate and are large enough to be returned to the wild to eclose as adult butterflies to renew their reproductive cycles.

"Bringing Woodland Park Zoo's entomology staff's experience and knowledge of invertebrate husbandry into the mix allows us to develop effective and efficient techniques to raise the larvae," explains Woodland Park Zoo curator Greg Toffic. "The care of each individual is a time-consuming process. Once the headstarting techniques have been perfected,” notes Toffic, “the zoo will begin teaching other institutions how to replicate the procedure." Through such efforts and the protection of damaged grasslands, this beautiful and native species may once again fill our skies with color.

As refinements in breeding techniques, habitat restoration, and other important factors improve with ever-increasing research and knowledge, many more species may benefit from captive breeding and release programs.

Butterfly populations in the Northwest and throughout North America are in decline with 22 butterfly species listed as either endangered or threatened. To address this problem, Woodland Park Zoo, in cooperation with the U.S. Fish & Wildlife Service, American Zoo and Aquarium Association, and 34 zoos and aquariums from around the country, has formed the Butterfly Conservation Initiative. The initiative program is designed to bring together non-governmental organizations and government agencies to aid the recovery of North American butterflies.