Zerene Fritillary (Speyeria zerene [Boisduval])
Wing span: 2 1/8 - 2 3/4 inches (5.4 - 7 cm).
Identification: Upper surface of both wings tawny to red-brown with dark markings. Underside of hindwing has silvered or unsilvered marginal spots more triangular than those of Speyeria coronis.
Life history: Males patrol all day seeking females. Females may delay egg-laying until late summer. Eggs are laid on leaf litter near violets; unfed first-stage caterpillars overwinter on a silken mat. In the spring, caterpillars feed on leaves of violets.
Flight: One brood from mid-June to early September.
Caterpillar hosts: Violets including Viola adunca, V. lobata, V. cuneata, V. nuttallii, and V. purpurea.
Habitat: Conifer forests, sagebrush, coastal meadows and dunes.
Range: Coastal British Columbia south and east to Montana, south to central California, Arizona, and New Mexico.
The Oregon silverspot (subspecies hippolyta) is historically known from 17 locations along the Pacific Coast from southern Washington to central Oregon, but is now found in only 4 sites in Oregon. Habitat loss and intrusion of non-native plants have been accelerated by increased recreational use and development of the coast.
Speyeria zerene hippolyta is listed as T1 by The Nature Conservancy: Critically imperiled because of extreme rarity (5 or fewer occurrences, or very few remaining individuals), or because of some factor of its biology making it especially vulnerable to extinction. (Critically endangered throughout its range).
The Myrtle's silverspot (subspecies myrtleae) and Behren's silverspot (subspecies behrensii) are listed by the United States Fish and Wildlife Service.
Management needs: Establish Critical Habitat areas where encroaching development and plants can be managed to preserve meadows where the caterpillar host plant (Viola adunca) grows.
Matthews, J. R., editor. 1990. The official World Wildlife Fund guide to endangered species of North America, Vol. 2. Beacham Publishing, Inc., Washington, D. C. 636 pages. Scott, J. A. 1986. The butterflies of North America. Stanford University Press, Stanford, Calif. 583 pages, 64 color plates. Tilden, J. W. 1986. A field guide to western butterflies. Houghton-Mifflin Co., Boston, Mass. 370 pages, 23 color plates.
Author: Jane M. Struttmann
State and Regional References:
Brown, J.W., Real, H.G., and D.K. Faulkner. 1992. Butterflies of Baja California. Lepidoptera Research Foundation, Beverly Hills, Calif. Comstock, J.A. 1927. Butterflies of California. Privately published, Los Angeles, Calif. [Facsimile available from Entomological Reprint Specialists, Los Angeles, Calif.] Dameron, W. 1997. Searching for butterflies in southern California. Flutterby Press, Los Angeles, Calif. Emmel, T.C. Editor. 1998. Systematics of western North American butterflies. Mariposa Press, Gainesville, Florida. Emmel, T. C. and J. F. Emmel. 1973. The Butterflies of Southern California. Natural History Museum of Los Angeles County Science Series No. 26. Garth, J.S. and J.W. Tilden. 1986. California Butterflies. California Natural History Guide 51. University of California Press, Berkeley and Los Angeles. Langston, R.L. 1981. The Rhopalocera of Santa Cruz Island, California. Journal of Research on the Lepidoptera 18: 24-35. Miller, Scott E. 1985. Butterflies of the Califorenia Channel Islands. Journal of the Research on the Lepidoptera 23: 282-296. Opler, Paul A. 1999. Peterson Field Guide to Western Butterflies, revised edition. Houghton Mifflin Co., Boston, Mass. Orsak, L.J. 1977. The Butterflies of Orange County, California. Museum of Systematic Biology, University of california, Irvine. Stanford, R.E. and P.A. Opler. 1993. Atlas of Western USA Butterflies. Privately published, Denver, Colo. Steiner, J. 1990. Bay Area Butterflies: The Distribution and Natural History of San Francisco Region Rhopalocera. Hayward, Calif.: Hayward State University, Masters Thesis. Tilden, J.W. and A.C. Smith. 1986. A Field Guide to Western Butterflies. Houghton Mifflin Co., Boston, Mass. Tilden, J.W. 1965. Butterflies of the San Francisco Bay Region. California Natural History Guide 12. University of California Press, Berkeley and Los Angeles.