The California Department of Food and Agriculture has quarantined parts of Napa, Sonoma and Solano counties after a European grapevine moth larva was trapped in Napa County in September 2009.
The quarantine encompasses 162 square miles, according to a news release.
The trap catch marked the first time the pest had been detected in the United States.
Subsequent surveys found the pest in two pockets—one on the eastern side of the city of Napa and the other between Oakville, Rutherford and St. Helena.
To view maps of the quarantine zone, click here.
The moth, known scientifically as Lobesia botrana, damages primarily grapes.But it has been known to feed on a host of other plants, including gooseberries, pomegranate, olives, persimmons and stone fruit.
It is endemic to southern Asia, Europe, North Africa and South America.
In the Oakville area of Napa County, where the original infestation was detected last fall, one grape grower lost his entire harvest, according to the news release.