Voracious ‘skeletonizer’ vineyard pest moth detected in Napa County

Katy St.Clair | Bay City News Foundation

Napa County authorities are sounding the alarm over a moth known to cause ‘significant’ damage to vines after an insect trapper discovered it earlier this month and l reported to the county commissioner of agriculture.

The moth, nicknamed with the rather heavy metal name “Western Grape Leaf Skeletonizer” is of the species Harissina metallica and is described by the county as a “voracious feeder” that can cause significant damage to grape leaves. , often resulting in partial or complete defoliation. of vines. Feeding can also damage fruit and lead to secondary fungal damage.

“We don’t want this pest to become established in Napa County,” said Tracy Cleveland, the county’s commissioner of agriculture.

Bug trapper Jesse Guidi was monitoring another pest in Pope Valley, the glassy-winged sniper, when he encountered the skeletonizer on May 12.

The commissioner ordered 25 additional traps to be used within a one-mile radius of Guidi’s discovery.

According to the county, the skeleton is not native to the area and was last seen in the Napa area in 2018. The pest first arrived in California from Arizona or New Mexico in the 1940s.

Authorities say evidence of the moth’s presence is fairly easy to spot, as only the veins of a leaf remain, producing a distinctly lacy appearance.

The skeleton also loves Boston Ivy and Virginia Creeper. In the larval stage, it displays colorful bands around its body.

Cleveland is asking Napa County residents who suspect they have found a Western Vine Leaf Skeletonization caterpillar or adult moth to bring it “immediately” to the county office or contact them for assistance. to identify it.

Grape growers, vineyard managers, wineries and residents are urged to inspect any farm equipment brought into the county to ensure it is also pest free.

The Napa County Agriculture Commissioner’s Office can be contacted at (707) 253-4357.

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