A single European grapevine moth has been found in Healdsburg, a county official announced Thursday.

The find is the third around Windsor and Healdsburg, though all three insects were trapped far enough apart that a federally mandated quarantine was not triggered. They must be within three miles of one another, Sonoma County Agricultural Commissioner Cathy Neville said Thursday.

A quarantine area will be established due to grapevine moths found this spring around Kenwood and Sonoma. Officials originally predicted that each community would have its own, but Neville said new rules will likely bring Kenwood and Sonoma into one larger quarantine area.

Grapevine moths, native to Mediterranean Europe, were first confirmed in the U.S. in September, when they were spotted in Napa Valley. The insects destroyed the crop in one Oakville vineyard and damaged other vineyards. Moth larvae burrow into and feed on the berries, often infecting the fruit with botrytis, or bunch rot.

Growers in quarantine areas can still ship their grapes to market, but they must agree to inspections or to rules that ensure they don't help spread the moth. Those rules have yet to be formalized.

More than 29,000 moths have been trapped this year in Napa County.

The moths also has been found in Mendocino, Solano and Fresno counties.

Neville said her staff is planning to reach out to Healdsburg residents near the latest discovery. She wants them to know about the pest and its reliance on grapevines. She also will seek cooperation as agricultural inspectors begin to put up more traps nearby.