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Larvae of the Western Grapeleaf Skeletonizer moth

Larvae of the Western Grapeleaf Skeletonizer moth.

Napa County is asking the wine industry and residents alike to be on the lookout for an ominous new pest in the vineyards.

In a newsletter this month, the Napa County Agricultural Commissioner’s office reported having trapped a lone Western Grapeleaf Skeletonizer moth in a Calistoga vineyard in June.

In its newsletter, the office called the Skeletonizer “a significant and destructive grapevine pest,” whose larvae threaten major leaf damage and defoliation of vines, with younger plants particularly at risk. If the pests’ feeding goes unchecked, fruit damage and grape cluster rotting can follow.

The single discovered insect was an adult male, the office said, and was found in a vineyard trap along Tubbs Lane. In turn, Ag Commissioner staff placed traps throughout the area, laden with pheromones to attract more males from a range of one and a half miles away. The office said it plans to continue trapping for the rest of the growing season and will add on more traps next year.

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Trapping was carried on much the same way when the Skeletonizer was first sighted in the same area in 2015, the newsletter read, yet no further moths were found then. For now, the Ag Commissioner’s office is urging growers, wineries and county residents to learn how to spot the moth and its larvae, which can also be found on wild and backyard grapes, as well as Boston ivy and Virginia creeper.


Wine Reporter / Copy Editor

Henry Lutz covers the local wine industry. He has been a reporter and copy editor for the Register since 2016.