Speyeria zerene
Zerene Fritillary

Family:Nymphalidae
Family Description:
Note: This species is comprised of many subspecies.


Description:
Caterpillar:
The caterpillar varies in color from yellowish gray to orange, and has a black head. It is heavily marked with brown or black patches and with a dark (possibly light) line down the midline. The body is covered with grayish spines.
Adult: The Fritillaries as a group are very similar in appearance, and the differences between individual species are often minor and difficult to see. Positive identification to the species level is difficult and requires detailed examination. This is a medium-sized Fritillary, with a wingspan of 1 7/8 to 2 3/4 inches. Its appearance varies somewhat regionally. The upperside ranges in color from golden orange to reddish orange to orangish brown and is bordered with two thin black lines. The forewing is marked with short, wavy, nearly parallel black lines. There is a vertical, wide, wavy and wandering black line across the wing’s center, followed by a row of black spots, followed by a row of black, inverted "v"-shaped marks along the outside edge. The wing veins are outlined thinly in black, and the hindwing is similarly marked. Underneath, the forewing is golden yellow, tinged with orange at the base, and with several small patches of brown at the tip. It is marked as above, but also with several silver spots at the tip and along the upper half of the outer edge. The hindwing is usually brown and may be edged with a wide yellow band. The base may be tinged with violet, green, or yellow (often in our area). It is marked with large silver, possibly white or yellow, spots. The spots on the outer half of the wing are arranged in two curved rows; the spots in the outermost row appear flattened.

Range:
This species ranges from the coast of British Columbia south to California, east to Montana, western Nebraska, and northeastern Colorado. It occurs through most of Idaho.

Habitat:
It occurs in a variety of habitats, including coastal dunes and meadows, conifer forests, and sagebrush steppe.

Diet:

Caterpillar: Caterpillars feed on the leaves of several species of violets (Viola spp.).
Adult: Butterflies drink flower nectar.

Ecology:
There is one new generation of caterpillars each year. Eggs hatch in the fall; the newly emerged caterpillars, having not yet fed, enter a physiological state called diapause to overwinter. In the spring the young caterpillars feed on the new leaves of host plants. The caterpillar has needle-like extensions on its spines which are hinged and can be folded upward by the caterpillar. The caterpillar is also equipped with a gland which releases a musky smell that may be repulsive to ants. Adults generally fly from the end of May to September. In California, adult females have been observed entering diapause during the summer before laying eggs, then emerging in late August to September to oviposit. Fritillaries are long-lived for a butterfly, surviving several weeks to months.

Reproduction:
Males patrol all day in search of receptive females. pheromones, chemicals used to locate and attract the opposite sex, are produced by both male and female Fritillaries. These chemicals are believed to play an important role in assisting these butterflies to find and recognize other members of their own species. Eggs are laid singly near host plants. In cases where the violet plant has already withered and blown away, females are still able to lay their eggs near to where the host plant will reappear the next spring. This is possible, it is believed, because females are able to locate violet roots by smell!

Conservation:
Idaho Status: Unprotected nongame species.
Global Rank:

Varies with subspecies. Speyeria zerene hippolyta, the Oregon Silverspot, of the Pacific Northwest coast is listed as T1, which means it is critically imperiled because of extreme rarity and is imminently vulnerable to extinction. Additionally, California subspecies myrtleae, the Myrtle’s Silverspot, and subspecies behrensii, Behren’s Silverspot, are both listed as Endangered by the U.S. Fish and Wildlife Service.


References:
Ferris, C.D. and F.M. Brown (eds.) 1981. Butterflies of the Rocky Mountain States. Univ. of Oklahoma Press, Norman, Oklahoma, USA, 442 pp.

Opler, P. A., H. Pavulaan, and R. E. Stanford. 1995. Butterflies of North America. Jamestown, North Dakota, USA: Northern Prairie Wildlife Research Center Home Page. http://www.npwrc.usgs.gov/resource/distr/lepid/bflyusa/bflyusa.htm (Version 05Nov98).

Opler, P. A. and A. B.Wright. 1999. A Field Guide to the Western Butterflies.   Second Edition.  Peterson Field Guide Series. Houghton Mifflin Company, New York, New York, USA, 540 pp.

Pyle, R. M. 1981. National Audubon Society Field Guide to North American Butterflies. Alfred A. Knopf, Inc., New York, New York, USA, 924 pp.

Scott, J. A. 1986. The Butterflies of North America. Stanford University Press, Stanford, California, USA, 583 pp.

Stanford, R. E. and P. A. Opler. 1993. Atlas of Western U.S.A. Butterflies (Including Adjacent Parts of Canada and Mexico). Published by authors, Denver, Colorado, USA, 275 pp.