Classification and Range
Silverspots require one of three types of grasslands: coastal salt spray meadows, stabilized dunes or montane meadows. There are only eight remaining locations where suitable habitat and the silverspot occur. The grasslands that silverspots inhabit provide larval host plants, adult nectar sources and wind protection

Reproduction
Adults appear throughout the late summer and early fall, to search out members of the opposite sex with which to mate. Once a male locates a female, both fly 66-100 feet (20-31 m) above the ground, as they frantically flap their wings. A receptive female descends to the ground. The male follows the female to the ground, where they mate. The entire mating process takes only a few minutes. The female usually deposits her eggs underneath the violet host plants in ground level vegetation.

A silverspot female can lay as many as 214 eggs with a 60% fertility rate. When the eggs first appear, they have a cream color. Fertile eggs darken to a pinkish tan by the second day. The eggs hatch from 16 to 26 days after laying. After hatching, the larvae find a place to spend the winter in a resting state called diapause, similar to hibernation.

Life Cycle
In the spring, the caterpillars awaken from diapause and begin to feed on the leaves of the violets. The larvae go through six stages of development before pupation. The butterflies emerge from the chrysalis, a process called eclosion, between July and September. The timing of the life cycle is dependent on weather conditions.

The silverspot was declared a federally threatened species on July 2, 1980 and is classified as endangered on Washington Department of Fish and Wildlife's Species of Concern list. Several natural and manmade factors challenge the survival of the Oregon silverspot butterfly. As human population growth continues, it quickly encroaches upon and affects the habitat of the silverspot butterfly. Some of the main problems facing the silverspot:

• Natural fires, wind, and salt spray maintain grasslands of silverspot habitat. As civilization closes in on the silverspot's habitat, humans usually control the fires needed to burn invading trees and shrubs before they can have the necessary effect. Roads cut through butterfly habitat cause highway mortality. The butterflies run into windshields and grills of passing vehicles. Pesticides sprayed in butterfly habitat affect the survival of the butterflies. Catastrophic weather conditions can decimate an entire year's new population. Humans introduce exotic plants that crowd out the butterfly's native food sources. Some exotic species, such as Scotch broom, have no natural enemies in their new environment. Continued development of coastal front property for buildings, parks, use by off-road vehicles, or for grazing by livestock eliminates butterfly habitat.
• As silverspot populations decrease, the genetic diversity of the species also diminishes. This causes genetic problems that reduce the survival rate of the already small populations.

All of these factors (except weather conditions) are controllable. In order to ensure the survival of the silverspot butterfly, it will require a concentrated effort to preserve their habitat. Currently, several agencies work to restore habitat to its natural state. Because of its threatened status, the silverspot benefits from government protection.

Oregon Silverspot Butterflies Project
In 1999, the U.S. Fish & Wildlife Service (USFWS) revised a recovery plan for the silverspot. It started a captive rearing and release program in partnership with Oregon Zoo and Lewis and Clark College. Butterflies are released at Rock Creek and Cascade Head in Oregon, where patches of violets remain abundant.

In addition, the Nature Conservancy collaboratively works with U.S. Forest Service to restore native butterfly habitat through small, controlled forest fires. Scientists hope to re-establish early blue violets, so that the butterfly population can return to its historic numbers and ranges.

Both Woodland Park Zoo (WPZ) and Oregon Zoo directly aid the effort by headstarting the butterflies. This process is somewhat similar to WPZ's long-standing western pond turtle headstart program, which hatches and raises young turtles in zoos until they are large enough to escape predation in the wild.

Silverspot butterflies from Cascade Head and Rock Creek were induced to lay eggs in a laboratory. These butterflies were captured toward the end of their life cycle, having already bred and laid eggs in the field before being brought to either zoo. Every day, keepers feed the butterflies ‘nectar’, a solution of sugar, water and egg whites on saturated cotton balls.

As of January 2003, approximately 1,500 eggs have been laid at WPZ and over 800 have hatched. Each hatched larva is about .08 inches (2 mm) long and, under a microscope, appears to be a perfect miniature caterpillar. At this stage, keepers place the larvae in specially designed containers, and put them into a refrigerator for winter diapause. After winter dormancy, the butterfly larvae feed on western blue violet leaves. Soon thereafter, they pupate and are large enough for return to the wild to eclose as adult butterflies in renewal of their reproductive cycles.

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 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, WPZ, in cooperation with the USFWS, Association of Zoos & Aquariums, and 34 zoos and aquariums from around the country, formed the Butterfly Conservation Initiative. The initiative brings together non-governmental organizations and government agencies to aid the recovery of North American butterflies.

For more information, visit the Silverspot Butterfly page in our Conservation Section.

How You Can Help!
Humans need insects. Often unnoticed, silverspot butterflies and other insects are essential for maintaining the balance in nature and health of the living world. Here are only a few of the benefits insects provide:

• Butterflies, bees, and other insects pollinate wild plants and our crops, ensuring the production of seeds and fruits required for the continued survival of plants and animals. Earwigs, beetles and other insect scavengers clean up the environment by consuming decaying plants and animals. Scavengers recycle nutrients back into the soil, helping future generations of plants to grow. Many species of carnivorous beetles, ants and wasps eat other harmful insects that damage or destroy our crops and spread disease. Burrowing insects aerate and enrich the soil. Insects are a source of food for animals, including humans!
• Insects produce products used by people, including honey, beeswax, silk and dyes, to name only a few.

The effort to save animals and their habitat requires cooperation and support at the international, national, regional and individual levels. You can help in this cause. Join and become active in WPZ and other conservation organizations of your choice. To conserve habitat for beetles and other insects, reduce your use of pesticides and herbicides, and work to preserve vegetation in your neighborhood and in tropical regions.

Contact Woodland Park Zoo at webkeeper@zoo.org to find out how you can support conservation efforts at the zoo. Learn other ways you can help conserve wildlife and the habitats they require for survival by visiting our How You Can Help page.

Sources and Suggested Reading
Arnold, R.A., 1988. Ecological and behavioral studies on the threatened Oregon silverspot butterfly at its Rock Creek, Cascade Head, Mt. Hebo, and Clatsop Plains populations in Oregon. U.S. Fish & Wildlife Service, Endangered Species Office. Olympia, WA.

McCorkle, D.V. and P.C. Hammond, 1988. Biology of Speyeria zerene hippolyta (Nymphalidae) in a marine modified environment. Journal of the Lepidopterist's Society 42(3): 184-195.

Taxonomic classification varies between references. Classification information used in this fact sheet was taken from the U.S. Fish & Wildlife Service at: http://www.fws.gov/endangered/.