Costco Flowers and Garden Alerts: What Members Must Know Before Buying Plants

Discover the essential facts on Costco Flowers and Garden Alerts: What Members Must Know Before Buying Plants in this special report.

The insect at the center of the recent warnings, the glassy-winged sharpshooter (Homalodisca vitripennis), is a large leafhopper native to the southeastern United States. Measuring roughly half an inch long with dark brown bodies and translucent, veined wings, these insects feed heavily on plant xylem fluid. The insect itself does not kill the plant through feeding alone; rather, it acts as an aggressive vector for Xylella fastidiosa.

This bacterium produces Pierce's disease in grapevines. Once injected into a vine's water-transporting xylem vessels, the bacteria multiply and secrete a gel-like matrix that blocks water flow, causing leaves to scorch, wither, and drop. Infected vines typically die within two to four years, and there is no cure.

In late May 2026, inspectors in Northern California detected the pest on plants displayed inside retail warehouses in Sonoma and Napa counties, as detailed by regional agricultural reports from KRON4. For a region whose premium wine economy generates billions in annual output, the presence of sharpshooters outside designated quarantine zones represents a severe hazard. While native sharpshooters fly short distances, the glassy-winged variant flies much farther, climbs higher, and feeds on over 300 plant species, making eradication exceptionally difficult once colonies take hold in local vegetation.