A pest considered a major threat to California’s vineyards and its $73-billion wine industry has been found on grapevines sold at Northern and Central California Costco stores between April 21 and May 21, according to authorities.
The glassy-winged sharpshooter, which was first identified and detected May 19 from grapevines sold at a wholesaler in Fresno, is a small invasive insect that can spread a strain of bacteria, Xylella fastidiosa, that kills grapevines by “clogging their water-conducting vessels (xylem).” The deadly plague is called Pierce’s disease. Several other strains of the bacteria exist and can infect other host plants, including citrus, stone fruits, almonds, oleander and some shade trees, according to the California Pierce’s Disease Control Program.
If the insect were left unchecked, the disease could cost the California wine industry $166 million annually, California Department of Food and Agriculture officials said in an email.
The insect can be identified by its flat triangular head, large eyes and clear wings. The head is brown to black and has several ivory to yellowish spots, which helps separate it from its native counterpart, the smoke-tree sharpshooter. The insect is often found on the stems of plants and grows up to about a half-inch as a fully grown adult, according to the University of California.
“While many vines have been intercepted and destroyed, locating the thousands that may still be in customers’ hands remains our top priority,” California Secretary of Agriculture Karen Ross said in a news release. “Anyone who purchased these vines should contact their local agricultural commissioner immediately.”
California’s wine grape industry supports more than 422,000 jobs statewide, according to the state agriculture department.
The glassy-winged sharpshooter was first reported in California in the early 1990s and is native to the southeastern U.S. and northeastern Mexico. The insect was first identified as a threat in August 1999, when more than 300 acres of grapevines in Temecula were infested with the glassy-winged sharpshooter and Pierce’s disease and subsequently destroyed, the state agriculture department reported.
Overall, the disease has cost growers and government agencies about $110 million a year in losses and compliance costs, according to a March 2025 report titled “The Costs of Pierce’s Disease in the California Grape and Wine Industry.”
At least half of the annual costs are spent fighting the native smoke-tree sharpshooter that is endemic to Napa Valley in Northern California; that insect is not as effective at carrying and transmitting Pierce’s disease, however, and does not cause as much damage. The other half is spent primarily to ensure that the glassy-winged sharpshooter remains in the southern part of the state, where wine grape production is not as valuable, according to Julian Alston, a distinguished professor emeritus of agricultural resources and economics at UC Davis.
“Most of the valuable wine production is in the northern part of the state or on the coast where the glassy-winged sharpshooter is not present,” Alston said.
Up to 13,000 grapevine plants containing the glassy-winged sharpshooter have been sold across a total of 24 Northern and Central California counties, the state agriculture department said.
“In addition to destroying infested stock still in Costco warehouses, CDFA is working with agricultural commissioners and conducting public outreach to locate vines sold to consumers across 24 counties, as well as neighboring at-risk counties,” state agriculture authorities said in a news release.
“Officials are responding to public reports, conducting inspections and public outreach, and trapping near stores and locations where purchased vines were taken. They are also ensuring that potentially infested plants are safely contained and disposed of,” the release said.
Costco has also been working with the state agriculture department to notify customers, issue refunds to those who purchased the grapevines and assisted in connecting them to local agricultural officials in the impacted counties “for inspection and disposal guidance,” the agency said in a notice about the pests.
Authorities are asking residents who purchased the grapevines in the affected counties to follow strict guidelines, including isolating the plant and wrapping it in double trash bags, and contacting their county agricultural commissioner.
