Two Light Brown Apple moths have been discovered in the Carneros District, prompting state officials to call for a quarantine.

The moths, pests that threaten a variety of crops grown in California, were found 1.5 miles apart. The moth in Napa County was found near Duhig and Ramal roads, south of Highway 121 and west of Domaine Carneros. The second was nearby in southeastern Sonoma County.

The California Department of Food and Agriculture will set up separate quarantine areas for the two counties. The exact boundaries will be announced by the state sometime this week.

Under a state quarantine, farmers can still harvest and sell their crops, but must inform buyers of the quarantine and ensure steps are taken to prevent the possible spread of the pest.

Greg Clark, assistant agricultural commissioner in Napa County said, “We are contacting growers and wineries to let them know what is going on.”

The Light Brown Apple Moth has an insatiable appetite for many agricultural crops — including winegrapes. It is the No. 1 pest affecting winegrapes in Australia and New Zealand.

The moth in Napa County was discovered on July 23, and the Sonoma County pest was found Aug. 10.

In Napa County the likely quarantine area impacts 55 farmers — 53 are grapegrowers, one farms olives and the last has pasture land, according to the Napa County Agricultural Commissioner’s office. The area encompasses about 6,800 acres.

More traps are being put out in the quarantine area.

“We don’t know how the moths got here,” said Dave Whitmer, agricultural commissioner for Napa County. “We just hope there is not an infestation.”

Whitmer said winds could have blown the moths in or the pest could have hitched a ride on a vehicle. “No one knows for sure how it got here,” he said.

Discovery of the pest comes as harvest has gotten under way in Carneros and around the valley. So far, though, only some sauvignon blanc and grapes for sparkling wines have been harvested.

As a result of the quarantine, growers will have to tell the wineries they sell to that the grapes come from a quarantined area, and wineries will be asked to crush those grapes as quickly as possible.

“We don’t expect there to be a huge impact. This type of communication already occurs between the growers and wineries,” Whitmer said.

Wineries will have to take the green waste from the crush to a state compost facility instead of spreading it between the vines.

Jennifer Putnam, executive director of the Napa Valley Grapegrowers, said, “At this point we are working with the ag commissioner for the best course of action. They are aggressively trapping, and we are in conversations with Sonoma officials.”

The pest was previously found in American Canyon in spring 2008 and off Kelly Road in south Napa County in the fall of 2007.

Light Brown Apple Moth has an diverse appetite, eating crops, native species and landscape plants, according to the California Department of Food and Agriculture. The pesky pest’s diet ranges from alfalfa, alders and acacias to broccoli, lavender and roses — along with citrus, olives, tomatoes and trumpet vine.

“For people shipping commodities, this is serious,” Clark said.

The insect can reduce quality and yields of winegrapes and is found throughout the Bay Area and as far south as Monterey County. Thus far, the pest has not been found in the breadbasket of the San Joaquin and Sacramento valleys, according to Whitmer.

If there is another Light Brown Apple Moth discovered in the area, a federal quarantine is possible.