Invasive Beetle has Killed Over 200,000 Southern California Oak Trees, Raising Wildfire Risk

Goldspotted Oak Borer (GSOB) beetles have killed at least 200,000 oak trees across Southern California, with new infestations now confirmed in Ventura County. As reported by Brianna Ruffalo, CAL FIRE officials say the invasive beetle continues to expand its range, likely aided by the transport of infested firewood. The pest, native to Arizona and first detected in San Diego in the early 1990s, was spotted as far north as Ventura County for the first time in 2025.

Oaks are considered a keystone species because they provide essential wildlife habitat and natural fire protection. CAL FIRE forest pathologist Kim Corella explained that trees suffering significant crown loss are unlikely to survive. As mature oaks die, communities lose both habitat and a natural buffer against wildfire, since dried trees and fallen branches add fuel to fire-prone areas.

To slow the spread, CAL FIRE advises residents not to move firewood beyond county lines or more than 5 to 10 miles from its source. Officials recommend buying locally sourced firewood or ensuring it has been heat-treated to 140 degrees Fahrenheit for at least one hour. These preventive steps are critical to protecting the region’s remaining oak woodlands.