Once, it was one of the most abundant butterflies of the Southern California grasslands, numbering perhaps more than 100 million. Now it seems to have vanished.
The Wright's checkerspot, once common in parts of Orange County, may have become a victim of development and drought, of "lousy weather and the backhoe," said Dennis Murphy, director of the Center for Conservation Biology at Stanford University.
The last of the butterflies reported--two adults and two caterpillars--were seen in 1987 in the Gavilan Hills area of Riverside County, near Lake Mathews. Biologists have since searched several places where the butterfly was previously known, but without luck.
"It's in all likelihood gone, and it went without a whimper," said Rudi Mattoni, a biologist who has coordinated research on the insect. "It's conceivable that there's some stock around, but it's unlikely."
The last known Orange County colony of the butterfly was in Hidden Ranch near Black Star Canyon, but it was wiped out in a 1967 brush fire. Other colonies existed at Dana Point, Laguna Lakes and Irvine Regional Park, but none of the butterflies have been recorded there since the 1930s.
Wright's checkerspots (sometimes referred to as Quino checkerspots) were still abundant at numerous locations in San Diego and Riverside counties into the early '70s and had been found in Baja California. Entomologists also believe they may have lived in Los Angeles County before the turn of the century.
Now they appear to be gone everywhere. The primary reason, Mattoni said, is massive development of the butterfly's grassland habitat. Historically, colonies of the Wright's checkerspot ranged over a wide area, allowing the butterflies to adjust to changing climatic conditions by moving to a new location.
They Became Vulnerable
As the colonies were forced by development into smaller and more isolated areas, they became more vulnerable to natural environmental changes.
As development in Riverside and San Diego counties was escalating in the '70s, consecutive years of drought temporarily reduced the caterpillar's food supply, and several colonies of the Wright's checkerspot died out.
Colonies that survived into this decade have been decimated by further development and more years of less-than-average rainfall, Murphy said.
Last year, Murphy filed a citizen's petition with the U.S. Fish and Wildlife Service to give the Wright's checkerspot emergency protection under the Endangered Species Act. Seven months have passed, and the petition has been officially "warranted," which means that the agency considers the petition valid and will consider it.
Murphy concedes that it "it may have been too late." But he wants the Wildlife Service to proceed in case a colony of the butterflies is found.
Murphy holds out more hope than Mattoni does that the Wright's checkerspot is not yet extinct. Some caterpillars may still emerge from diapause, a form of hibernation in which the larvae can wait out a season or two of low food supply, or previously undiscovered pockets of the butterfly may still exist in Mexico, he said. But, he added, "I think there's a pretty good chance this thing is gone."
Demise Called 'Spectacular'
Mattoni, president of the Beverly Hills-based Lepidoptera Research Foundation, termed the butterfly's demise "spectacular" because while it was known that populations were declining, it wasn't until very recently that the severity of the problem became apparent. "What was a common butterfly fell through the cracks," he said.
Its former range and abundance sets it apart from other threatened butterflies and some that have become extinct, including the much-publicized Palos Verde blue, which were always limited to small areas.
Scientific name: \o7 Euphydryas editha quino \f7 (until recently referred to as \o7 Euphydryas editha wrightii).\f7
Alternate common name: Quino checkerspot.
Characteristics: Upper wing surface checkered with dark brown, reddish and yellowish spots.
Historic range: Orange, Riverside and San Diego counties and as far south as Ensenada in Baja California.
Habitat: Coastal mesa tops in grasslands, chaparral and around vernal pools.
Flight period: early March to early April (one brood per year).
Caterpillar's food: \o7 Plantago insularis; \f7 grows no taller than 3 inches, does not germinate in years of drought.
\o7 Source: "Butterflies of Orange County, California" by Larry Orsak, and Dennis Murphy, director of Center for Conservation Biology, Stanford University \f7