(PD) - Inspectors in Sonoma and Napa counties destroyed plants last week that contained egg masses of the glassy-winged sharpshooter, an insect that spreads a disease that can kill grapevines.

Napa inspectors on March 7 discovered the eggs on some plants that were transported to the Walmart Supercenter in American Canyon, said Napa County Agricultural Commissioner Greg Clark.

The shipment came from an Orange County supplier, Nakase Brothers Wholesale Nurseries of Lake Forest, Clark said.

Inspectors destroyed eight plants where the egg masses were found. No other problems were found on the remaining plants.

The next day, Sonoma County inspectors destroyed plants that also were found to have egg masses. They also were on the shipment from Nakase Brothers, according to Clark.

Local agricultural officials have been on guard for years against the glassy-winged sharpshooter because it can transmit Pierce’s disease into a grapevine. Besides the inspection programs, they also have carried out public education efforts.

The bacteria from the disease impede water flow in the grapevine and ultimately kills it.

Pierce’s disease has already forced some vineyard owners in both counties to pull out and replant their vines in recent years. The culprit in spreading the disease in those cases has been the blue-green sharpshooter, a relative of the glassy-winged sharpshooter, which thrives in mild winters and riverside areas. The two incidents last week were the first reports of the glassy-winged sharpshooter in the area this year.