Small beetles known as goldspotted oak borers (GSOB) have been newly detected in Ventura County, threatening the region’s native oak trees. These invasive insects have already killed hundreds of thousands of oaks across Southern California over the past two decades, including in San Diego, Orange, Riverside, San Bernardino and Los Angeles counties. Their spread is mainly attributed to people moving infested firewood.
Julie Clark, a community education specialist with UC Agriculture and Natural Resources (UC ANR), described the importance of oaks to local communities: “A lot of people move to Ventura County to live in these oak-studded communities. It’s an iconic species for the county,” she said. “The public can help protect and preserve the oaks from this devastating insect.”
Clark recounted how GSOB was first confirmed in Ventura County during summer 2024 after a local forester noticed a coast live oak showing signs of infestation—brown leaves and D-shaped exit holes on its trunk. The tree was classified as an “amplifier tree,” meaning it posed a high risk for spreading beetles to other nearby oaks. Clark explained that such isolated infestations are often due to people bringing infested firewood into new areas: “The beetles don’t fly very far. They spend most of their life inside the bark. So, infestations are almost always started by moving infested firewood.”
California does not currently restrict or penalize moving firewood between locations, despite concerns about spreading GSOB and similar pests. Scientists at UC ANR and professionals in tree care urge lawmakers to consider quarantines on infested wood but emphasize that until regulations change, individuals must take responsibility when handling firewood.
To control outbreaks, foresters removed affected trees by debarking and chipping them to destroy beetle larvae inside. However, GSOB continues to spread in Ventura County; another outbreak was found along Las Llajas Canyon Road in 2025.
To address knowledge gaps about current infestations, UC ANR is partnering with CAL FIRE for “GSOB Blitzes”—community science events where volunteers learn how to identify signs of GSOB activity and survey local parks and natural areas for symptomatic trees. The next event will be held on February 13, 2026 at Las Llajas Trailhead in Simi Valley.
“We need the help of the public,” Clark said. “That’s why we want to get people trained to observe and report possible GSOB.” She also highlighted that volunteering offers opportunities for learning and connecting with others: “You’re out in nature. You’re with people that are curious like yourself…It’s also an exercise in true community.”
Kim Corella, forest pest specialist at CAL FIRE, encouraged residents’ participation: “By participating in a GSOB Blitz, residents become part of the solution – helping detect infestations early, addressing local hazards while preventing the spread to neighboring communities and counties like Santa Barbara and San Luis Obispo,” Corella said.
Registration details for those interested can be found at https://surveys.ucanr.edu/survey.cfm?surveynumber=47507 . Additional information about ongoing efforts against goldspotted oak borer is available at www.GSOB.org .