University of California-Riverside entomology professor Thomas Miller holds a preserved glassy-winged sharpshooter in this 2004 file photo. Contra Costa County is trying to prevent an infestation of this insect from spreading after it was found present on plants sold by a number of Costco stores over the past month. " data-large-file="https://i0.wp.com/newspack-berkeleyside-cityside.s3.amazonaws.com/wp-content/uploads/2026/05/glassywingedsharpshooter_052826_ap.jpg?fit=780%2C522&ssl=1"> University of California-Riverside entomology professor Thomas Miller holds a preserved glassy-winged sharpshooter in this 2004 file photo. Contra Costa County is trying to prevent an infestation of this insect from spreading after it was found present on plants sold by a number of Costco stores over the past month.…