Napa County warns farmers of harmful moth discovery

A moth that can cause significant harm to vineyards was discovered in a trap on June 24 in Calistoga, Napa County officials said Monday.

Agricultural Commissioner Greg Clark warned farmers to be on the outlook for the Western Grapeleaf Skeletonizer, especially as they transport equipment and grapes into the county. The moth was found in a pheromone-baited trap, which can attract moths in a one-and-a-half mile radius.

'This is a destructive and serious pest,' Clark said in a statement. 'All larval life stages are voracious feeders that cause extensive damage to grape leaves, including partial or complete defoliation of grapevines. Excessive feeding can damage fruit and lead to secondary fungal damage and rot of grape clusters.'

Clark's office has deployed an additional 25 traps within a mile radius of the original discovery on Tubbs Lane. The moth, native to Arizona and New Mexico, was last found in Napa County in 2007.