Excerpts from Jim Conrad's
from the September 20, 2009 Newsletter, issued from the Siskiyou Mountains west of Grants Pass, Oregon:
FRITILLARY ON THE ASTERS
Above you can see a butterfly species that's been flitting around Anita's spectacular blue garden-asters this week. The moment I saw them I pegged them as fritillaries because of their similarity to the Mexican Fritillaries often seen during my Querétaro days, and the Gulf Fritillaries back in Mississippi. But, this one was different, so which species was it?
I'm guessing that it's the very variable Northwestern Fritillary, SPEYERIA HESPERIS, but it's awfully similar to other species that are mainly darker or paler than mine. My old Audubon field guide doesn't even list this species. Its picture of the Aphrodite matches it almost exactly but Aphrodites aren't supposed to occur in Oregon.
Trying to figure out the species online I found that the "Butterflies and Moths of North America" website has become much more complete and useful than in the past. It's at http://www.butterfliesandmoths.org.
On their main page I clicked on "Map Search," then on Oregon, and directly a page appeared listing Oregon's butterflies. Already I knew that my fritillary belonged to the genus Speyeria, so on the list I searched for Speyeria and found eight species listed. Each name was linked to its species page showing the butterfly in question, and with an Oregon county map indicating which counties the species has been reported from. After visiting each page I narrowed the possibilities down to "Northwestern Fritillary."
When not on Anita's garden asters, Northwestern Fritillaries live in forest openings, meadows, and on open hillsides in the Western mountains from central western Alaska, Yukon, and Northwest Territories south to central California, Arizona, and New Mexico. The caterpillars eat violets.