Speyeria zerene hippolyta (W. H. Edwards, 1879)
Date of listing: 1980
Federal Status: Threatened
State Status: None
As imperiled insects go, the Oregon Silverspot is in pretty good shape. It is federally listed as threatened rather than endangered. Fortunately, the threats to this butterfly’s habitats were recognized early enough so that drastic measures to ensure its continued existence are unlikely to be necessary.
Occurring along the coast in northern California and Oregon, the Oregon Silverspot requires a meadow species of violet (Viola adunca) to complete its development. Adults appear throughout the late summer and early fall at which time the sexes seek each other out for mating. The eggs are laid during the fall and hatch shortly thereafter. The larvae may feed for a short time in the fall and then enter a dormant state in which to spend the winter. In the spring the larvae come back out and resume feeding until some time in the late spring or summer when they pupate. Their pupation time is short and adults soon emerge and continue the cycle.
The Oregon Silverspot and its host violet are members of disturbance-oriented meadow communities. These meadow habitats historically have been maintained in an early successional state due to periodic fires. Fires prevent trees and shrubs from overshadowing low ground cover plants such as Viola. As development has made such periodic fires undesirable, they have been prevented and meadow gradually becomes forest. Recognition of the role of fire and other periodic disturbance in the maintainence of critical Oregon Silverspot habitat has allowed appropriate management strategies to be enacted and the butterfly’s future is relatively bright.
For further 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 and 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.