[caption id="" align="alignright" width="191" caption="Earlier stages of European grapevine moth larvae are tan to yellow-brown (top). Later stages become dark colored (bottom). (photo by Jack Kelly Clark, UC Statewide IPM Project, Regents, University of California)"][/caption]

NAPA VALLEY -- The state Department of Food and Agriculture today declared 162 square miles in two portions of Napa Valley and tiny portions of Sonoma and Solano counties under quarantine to control what's being called the first infestation of the European grapevine moth in the U.S.

The first detection of the moth in the U.S. was in the Oakville area on Sept. 15, destroying one grower's whole crop, according to the department. Trapping and field surveys delineated narrowed the infestation to 125 square miles north of Napa and 37 square miles east of the city.

Agricultural officials are planning informational meetings on quarantine procedures.

The north area extends from Deer Park Road in St. Helena south to Big Ranch Road and Solano Avenue just north of Napa. The south area stretches from Milliken Creek on the north to Skyline County Park on the south and from Jefferson Street in Napa on the west to portions of Green Valley in Solano County and eastern Napa County on the east.

Over three generations, the larvae disrupt spring flowering and thus winegrape crop size, burrow into grape berries and feed on the clusters, leaving the grapes open to rot. Adult moths don't destroy grapes directly.

Trapping for the moth is being conducted around the state. Host plants include olive trees, rosemary and red clover.

Internet resources

European grapevine moth information (Napa County Agricultural Commissioner)

Manual with maps of the quarantined areas (California Department of Food and Agriculture)