Santa Clara County Clear of GWSS for the First Time in 17 Years


Over the years, a number of small glassy-winged sharpshooter (GWSS) infestations have been eradicated in California. The latest eradication in Santa Clara County brings the total to 18 infestations that have been eradicated since 2000.

A yellow sticky trap.

Over the years tens of thousands of traps like this one high up in a tree were used to monitor and track the progress of the GWSS eradication program in Santa Clara County.

Santa Clara County has been particularly hard hit with GWSS infestations, with six of them since the first was detected in December 2001.

“We are very fortunate to have our tremendous staff return year after year to work on this program,” said Eric Wylde, Deputy Agricultural Commissioner for Santa Clara County. “And I have to say that, overall, we have also had great support from the residents and business owners who have been involved with this program for providing access to properties for inspection and/or treatment, irrigating prior to ground treatments, calling in suspect insects, and much more.”

tiny wasps that are released in newly discovered GWSS infestations

Inside this vial are just a few of the tiny wasps that are released in newly discovered GWSS infestations

When a GWSS is found on a trap in a new area, additional traps are put out to see if any more are in the area, and if so, what the boundaries of the infestation are. Often tiny parasitoid wasps are released in the area to help slow or stop further spreading of GWSS. The females of these wasps search out GWSS eggs and insert their eggs into the GWSS eggs. Inside the GWSS egg, the wasp’s egg hatches into a larva which then feeds on the GWSS egg. Soon a wasp emerges, and the process starts all over again.

Unfortunately, wasps can’t do it all alone. Treatment with insecticides is necessary, but before any treatments are begun, flyers are placed on all homes in the area notifying the public of why and how the treatments will be conducted. Also, a public meeting is held in the immediate area to help inform local residents about upcoming treatments.

Trapping continues until no additional GWSS are trapped in the area for two years. After two years of no GWSS being found, the infestation for that area is considered eradicated.

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