A non-native invasive shothole borer beetle found along Zayante Creek south of Graham Hill Road in October has been identified as Euwallacea interjectus, a beetle originating from Southeast Asia.
Prior U.S.-based identifications of Euwallacea interjectus have been restricted to states in the Southeastern part of the country. The species has not previously been identified in the Western United States. The taxonomy of Euwallacea interjectus was confirmed by the California Department of Food and Agriculture (CDFA).
Euwallacea interjectus are significantly larger than two invasive shothole borers previously known to exist in California. They leave behind larger entry holes but pose similar risks of tree dieback in urban, wildland and agricultural landscapes. So far, the Felton-area infestation has primarily impacted box elders, but California sycamore, coast live oak, arroyo willow, red willow, and black cottonwood have also been attacked.
Santa Cruz County Department of Agriculture and University of California Cooperative Extension are coordinating with CDFA to monitor and respond to the infestation. Research is being conducted by the University of California to evaluate the full range of potential tree species that may be affected by the beetle.
Officials recommend following guidance on the management and prevention of spread of other invasive shothole borer species to Euwallacea interjectus. Resources on the monitoring, detection, and management of ISHB, including a new factsheet on the identification and damage caused by Euwallacea interjectus, are available at ISHB.org. Further guidance and relevant trainings for arborists and natural resource managers will be announced as they become available.
To report suspected damage, call the Santa Cruz County Department of Agriculture at 831-763-8080. For help with management, contact the local Cooperative Extension Forest Advisor.
