The Oregon silverspot butterfly (Speyeria zerene hippolyta) was declared a federally threatened species on July 2, 1980. Although its native range is spread 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 at one site. Another factor that severely restricts its population is that its preferred food plant is the early blue or dog violet (Viola adunca). This beautiful little violet, once prevalent on Washington's Long Beach peninsula and other places, is now disappearing as its habitat is gobbled up by development.

In 1999, the U.S. Fish and 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 Cascade Head Preserve in Oregon. This site with still abundant patches of violets, was established by The Nature Conservancy. Now WPZ is also directly aiding the effort by headstarting silverspots here at the zoo, a process similar in some ways to our long-standing western pond turtle headstart program.

For the project, adult female butterflies are captured as they enter their egg-laying phase and transferred to WPZ. After the eggs hatch, the first stage, or instar, are put into winter diapause, a "hibernation" of sorts in insects, from September until May. In the meantime, violet plants are propagated by the Washington Department of Fish and Wildlife’s Dave Hays and then raised by horticulture students at Aberdeen High School.Then the plants are sent to the zoo for maintenance by zoo horticulture staff and by Seattle area students via WPZ's Wild Wise outreach program.

The plants are then fed to the butterfly larvae after they emerge at WPZ. After we rear them, the pupae are returned to the wilds where adult butterflies will emerge and renew their reproductive cycles. It is hoped that with the headstarting provided by the zoo, a greater survival rate of pupae will allow the wild populations to recover.

By bringing Woodland Park Zoo's entomology staff's experience and knowledge of invertebrate husbandry into the mix, effective and efficient techniques to raise larvae are developed. The individuals must each be cared for and fed in what is a time consuming process. Once these techniques are developed they will increase the number of butterflies that can be headstarted, and enable other institutions to replicate the procedure. Through these efforts, and the protection of damaged grasslands, this beautiful native species may once again fill our skies with color.

For more information about the Oregon silverspot butterfly conservation project, visit the Washington Department of Fish and Wildlife’s Endangered Species Web site at http://www.wa.gov/wdfw/wlm/diversty/soc/osbutter.htm

For more information on habitat restoration for the silverspots, visit the Friends of the Puget Prairie Web site.

(Oregon silverspot butterflies are not on exhibit in Butterflies & Blooms.)