Napa County Urges Residents to Check Grapevines Sold at Napa Costco Following Detection of Glassy-winged Sharpshooter

NAPA, California (May 26, 2026) – The Napa County Agricultural Commissioner’s Office is issuing an urgent public alert regarding grapevine plants sold at Costco Wholesale in Napa that may be infested with the glassy-winged sharpshooter (GWSS), an invasive insect pest that poses a serious threat to California’s vineyards.

Between April 21, 2026 and today, the Napa Costco Wholesale location received multiple shipments totaling 220 grapevines from Burchell Nursery, Inc., located in Fresno County. All life stages of GWSS have been detected on these shipments across multiple counties, including Sonoma, Marin, Solano, Yolo, and others.

To date, 63 of the 220 grapevines delivered to Napa Costco have been destroyed and one GWSS egg mass was found. The remaining 157 grapevines are unaccounted for and may be in the possession of community members who purchased them at Napa Costco.

Napa County Agricultural Commissioner Tracy Cleveland said “GWSS is a devastating pest for our local vineyards, and it is critical for us to track down any potentially affected plants purchased at Costco or brought into Napa County. I am confident that the community will pull together to help us limit the risk to our local agriculture. Vigilance and prompt reporting are essential”.

Costco is directly contacting members who purchased plants within the timeframe and has been a cooperative partner with all County Ag Commissioners.

GWSS can spread Pierce’s disease, a bacterial infection that is often fatal to grapevines and can significantly impact vineyard production. GWSS can damage almond, citrus, and ornamental plants. Early detection and containment are critical to protecting Napa County and California’s agricultural and viticultural resources.

If you purchased a grapevine, citrus tree, or other fruit tree at Napa Costco or neighboring Costco locations during April or May, you should:

• Keep the plant isolated in its original pot or container.

• Do not plant the grapevine or tree if you have not already done so.

• If possible, place the plant(s) in two secured trash bags, one inside the other, and seal them closed.

• Do not attempt to return, transport, or relocate the plant.

• Do not place the plant in the trash or a compost bin.

• Immediately contact the Napa County Agricultural Commissioner’s Office at 707-253-4357 or agcommissioner@countyofnapa.org.

• An agricultural inspector will be dispatched the same day to examine the grapevine, fruit tree(s) and any nearby host plants.

As a precautionary measure, GWSS monitoring traps may be placed on the property.

For more information about GWSS and Pierce’s disease, visit the California Department of Food and Agriculture.