A tiny insect is silently killing California's coast live oaks. First spotted in Ventura County last year, the goldspotted oak borer has already left a trail of dead trees across Southern California, reported KEYT. Experts say the beetle's reach could expand rapidly if residents and officials don't act.

What's happening?

Cal Fire confirmed multiple detections of the goldspotted oak borer in Ventura County earlier in January. The first Ventura County infestation was detected on a coast live oak along Box Canyon Road in August 2024. The infected tree was removed to try to stop the spread. Despite that, a second oak already dead from infestation was found in Santa Susana in April 2025, followed by additional dying trees along Las Llajas Canyon Road in May.

"Since its discovery in San Diego County in 2008, the invasive beetle species is estimated to have killed more than 200,000 mature oak trees as it has spread to San Bernardino, Riverside, Orange, Los Angeles, and now, Ventura counties," the agency said in a press release.

Why are infestations and dead trees concerning?

Goldspotted oak borers kill from the inside out. Larvae tunnel under the bark, feeding on the tree's living layers until large oaks collapse. 

"Large oaks can die within a few years after an initial infestation and are highly vulnerable once goldspotted oak borers are established in the region," Cal Fire explained.

The beetles often travel through infested firewood, making human activity a key driver of their spread. Once they establish in a region, the destruction can ripple through the ecosystem: Oaks provide food and shelter for birds, mammals, and insects, and their loss leaves gaps that are hard to fill. Dead or dying trees also increase fire risk and make landscapes more vulnerable to erosion. 

Because these insects are small and hard to spot, infestations can spread silently, leaving communities and wildlife scrambling to catch up once the damage becomes visible.

What's being done about the spread of the goldspotted oak borer?

Cal Fire, the University of California Agriculture and Natural Resources, the Ventura County Fire Department, and the Ventura County Department of Agriculture, Weights and Measures are coordinating efforts to track and respond to the beetle's spread. This includes removing heavily infested trees, monitoring new outbreaks, and educating the public about how the beetles move, especially through firewood.

According to UC Riverside, the beetles complete a lifecycle each year, with mature larvae visible from late May through October, underscoring the need for vigilance.

By understanding which trees are most vulnerable, scientists hope to slow the beetle's expansion and protect oak populations across the region.

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