Costco sold desert willow plants with invasive insects in California

Costco issued a warning to customers who purchased desert willow plants at certain California locations from June 24 through July 3. The plants may carry the glassy-winged sharpshooter, an invasive insect that can spread a bacterium causing Pierce's disease, which is fatal to grapevines.

The company directed buyers to isolate the plants immediately, keep them in the original pot away from other vegetation, and contact their county agricultural commissioner's office. Officials asked customers not to return the plants to stores but said they can present the warning letter for a full refund.

Background on the pest The glassy-winged sharpshooter is native to parts of North America including northeastern Mexico and is considered invasive in California. While feeding on plant fluids, the insect can transmit the bacterium that causes Pierce's disease, which has previously damaged vineyards in the state.

The California Department of Food and Agriculture stated that early detection and rapid response are critical to preventing further spread. The pest can also damage citrus trees, landscape plants, and other crops.

Prior incidents and response This is the second known infestation linked to plants sold at California Costco warehouses in recent months. Earlier this year, the same insect was found on grapevines sold at select Northern California locations, prompting officials to destroy affected plants still at warehouses and conduct outreach to locate sold plants.

The infested grapevines were shipped from Fresno to warehouses in 24 Northern California counties in April and May. The infested willow plants were sold in 15 counties, mostly across Southern and Central California. California officials first identified the threat in 1999 after a Pierce's disease outbreak in the Temecula Valley destroyed more than 300 acres of vineyards.