Hungry grapevine pest pops up in Napa Valley

A destructive moth with the ominous name of the Western Grapeleaf Skeletonizer has been found in a vineyard trap in Calistoga, the Napa County Agricultural Department said today.

The voracious, non-native moth was found in a vineyard trap June 24 on Tubbs Lane in Calistoga, Agricultural Commissioner Greg Clark said:

“This is a destructive and serious pest. All larval life stages are voracious feeders that cause extensive damage to grape leaves, including partial or complete defoliation of grapevines. … Extensive feeding can damage fruit and lead to secondary fungal damage and rot of grape clusters. We do not want this pest to become established in Napa County.”

The moth has been found a number of times in Napa County, including a 2007 discovery on Mt. Veeder Road, the Agricultural Department said.

Twenty-five additional traps have been set within a one-mile radius of the Calistoga find, Clark said.

The moth is native to Arizona and New Mexico and was first discovered in California in the 1940s. It eventually spread throughout the state, particularly in the Central Valley.

When the Skeletonizer feeds on grapevines, it leaves only the veins, producing a very distinctive, lacy skeletal appearance. It can also be found on Boston ivy and Virginia creeper, the Agricultural Commissioner’s Office said.

Anyone who believes they have found the Western Grapeleaf Skeletonizer caterpillar or adult moth should bring it to the Agricultural Commissioner’s Office or contact the office to help identify it.

Vineyard managers, wineries and residents who may be transporting farm equipment or winegrapes into Napa County are asked to inspect their farm equipment to make sure it is free of the Skeletonizer or any wine grape pests.