SAN FRANCISCO -- Full grown, the light brown apple moth is about half the size of a quarter: a little dirt-colored insect with an adult life span shorter than the average summer vacation.
But, oh, what an eater. As a caterpillar, the moth feeds on flowers, fruits and firs, a menu that can include corn and tomatoes for dinner, and cherries, peaches and plums for dessert. So omnivorous is the moth that some entomologists call it the "light brown everything moth."
It is exactly that appetite that has state and federal officials in California worried. A native of Australia, the moth had not been seen in the continental United States before February, when a retired entomologist discovered one in a trap behind his house in Berkeley, just across the bay from here and within fluttering distance of one of the nation's most important agricultural regions.
The moth has since been found in nine California counties, including Napa, where the discovery of a single specimen set off alarm bells for winemakers and farmers.
"It is a significant pest of wine grapes, and because that's what we grow, that's what caught our attention," said Greg Clark, assistant agricultural commissioner in Napa County. "And if we have an infestation here, it's likely it could move into other agricultural regions."
Over the years, California has faced a number of threats to its agriculture. Perhaps the most famous invasive pest was the Mediterranean fruit fly, or medfly, which prompted a statewide panic - and aerial spraying - in the early 1980s, when it appeared to be threatening the state's billion-dollar citrus industry.
No one is predicting that kind of response this time. Then again, no one is taking the chance. "People want to see this pest dealt with quickly and decisively," Clark said. "Because there's always another pest over the horizon."
Spraying began recently in Oakley, a Bay Area suburb where masked workers went bush to bush with organic pesticides, with further treatments planned for today in Napa, thought to be the northernmost border of the moth invasion.
The problem seems even more serious to the south in Santa Cruz County, where nearly 3,500 moths have been discovered and where farmers and agricultural officials have set thousands of traps in wholesale nurseries to try to safeguard the county's $73 million industry in shrubs, trees and other ornamental flora. Statewide, agricultural officials say California could lose more than $100 million because of increased production control and pest control.
Chief among growers' concerns is the possibility that foreign markets will begin to reject California crops. To that end, the federal Department of Agriculture and the California Department of Food and Agriculture have declared quarantines for the affected counties, barring the transportation of crops or plants around the state without inspections.
Like many states, California is dealing with a variety of other invasive pests and diseases, each with a more evocative name than the last, like the glassy winged sharpshooter (which can be devastating to citrus groves and vineyards) and the red imported fire ant, a nasty little insect whose bites can result in pain and welts.
Officials say they do not know how the moth got here, but that it may have come via a host plant brought by a homesick emigre. "California is a popular place, and people come and bring their favorite plant along," said A.G. Kawamura, California's secretary of agriculture. The moth infestation has also renewed cries from officials like Kawamura who believe that agricultural border inspections should be returned to the province of federal agricultural officials. The job is performed by the Department of Homeland Security, which some critics say does not have the expertise to spot incoming pests like the moth. Sen. Dianne Feinstein, a California Democrat, recently introduced a bill in Congress to move inspections back to the Department of Agriculture.
Russ Knocke, a homeland security spokesman, disputes the notion that the federal agriculture agency would do a better job. "If someone in this department said everything is working properly and everything is perfect, that person should be removed," Knocke said. "But for someone to express that rearranging the deck chairs - again - is going to be the solution, I'm going to flatly reject it."
Regardless of its method of entry or which agency ultimately takes the lead, getting rid of the moth is going to be a challenge. James R. Carey, a professor of entomology at the University of California, Davis, said that eradication efforts were often fruitless, particularly when large numbers of insects had been found.
"These pests can be there at subdetection levels for years, if not decades," said Carey, who worked on the medfly infestation. "They operate - cancer is a good analogy - they operate in little pockets and then boom, the conditions come together, both climatic and microevolution, and then they appear."