February 7, 2025
GLASSY-WINGED SHARPSHOOTER PROGRAM 2025 SEASON BEGINS
FRESNO….. March 2025 marks the start of the Glassy-winged sharpshooter (GWSS) treatment and biological control program in Fresno County. Our control strategy remains focused on targeted suppression, aiming to halt the spread of this destructive pest through effective treatments and biocontrol measures. This effort will reduce the impact on ornamental landscapes and mitigate the serious threat to California’s $6.52 billion-dollar grape industry (2023 crop year gross value).
The GWSS causes severe damage by feeding on a wide range of ornamental and crop plants. They prefer to feed on stems rather than leaves, using their strong sucking mouthparts to extract fluids and nutrients from plants. Additionally, they can transmit various plant diseases, including Pierce’s Disease, which kills grapevines and currently has no effective treatments.
The adult GWSS is a sizable insect, roughly ½‑inch long, with a dark brown to black body and a lighter underside. Its wings are partly transparent with reddish veins. Newly emerged adults and nymphs appear grayish to light brown. The nymphs do not have fully developed wings.
For those properties within Fresno County’s treatment areas, keep an eye out for a postcard arriving soon with details about a virtual meeting. This meeting will provide more information and an opportunity to ask questions of both State and County GWSS program staff. Beginning March 10, 2025, homeowners in areas surrounding known GWSS discoveries will be requested to allow voluntary treatment on their properties. Weather permitting, treatment will begin on March 17, 2025. The treatments will involve applying a systemic insecticide by drenching the soil directly beneath certain landscaping host plants and non‑commercial citrus trees, which are GWSS’s preferred host for over‑wintering and egg‑laying; as well as a foliar application of the same systemic insecticide to non‑commercial grapevines.
GWSS trap in backyard citrus
Trap in a commercial orchard
Trapping with yellow sticky panels will begin in May. As in previous years, traps will be placed in plant nurseries, commercial citrus and grapes, and residential landscape throughout Fresno County. Biological control efforts will continue through the release of a very tiny wasp that parasitizes GWSS eggs. Areas identified as “good candidates” for biological control will be determined through consultation with the California Department of Food and Agriculture and the County of Fresno Department of Agriculture’s Entomologist.
Each County of Fresno Department of Agriculture employee carries an identification badge, which they are required to wear while on duty. Residents and growers are encouraged to ask employees for their official identification badges. If you think you have found GWSS or have questions about our trapping, surveying, host treatments, or parasitoid release efforts, please call the County of Fresno Department of Agriculture GWSS Program Office at (559) 470‑8188.