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The state’s most lucrative crop, grapes, has yet another insect enemy.

The California Department of Food and Agriculture quarantined 162 square miles in Napa Valley on Tuesday in an effort to stop the spread of the European grapevine moth, the newest threat to grapes and other fruit.

The quarantined zone spans parts of Napa, Sonoma and Solano Counties. Grapes within the zone cannot be transported outside the quarantine boundaries, though the grapes can be processed on site.

Last year the state’s grape harvest was worth $2.74 billion, about a third of which was generated in the valley.

The moth was discovered in a vineyard insect trap in September, the first appearance by the species in the United States, the department said. The larvae feed mainly on grape flowers and young grapes but can also damage some 21 other crops including olives, kiwis and persimmons.

“The wine industry is very important to our region,” said Elizabeth Emmett, a spokeswoman for Napa County. “We are going to try to do everything that we can to eradicate this nonnative pest.”

A native of Italy, the moth has caused crop damage across Europe, as well as in parts of Africa, Asia and the Middle East.

The European grapevine moth is the latest in a spate of invasive insects to hammer California’s wine industry, including the light brown apple moth and the glassy-winged sharpshooter. Because of its preferred fare, the moth has grape growers particularly worried.

State agricultural officials have set up some 2,500 traps across Napa Valley to capture the moths, said Jennifer Putnam, director of Napa Valley Grapegrowers, a nonprofit trade group, which is helping to coordinate the response.

In the next several weeks, dispensers containing the pheromones of female moths will go into the fields to confuse the males and disrupt the insects from mating. Long-term eradication and management plans are still being worked out.