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gold-spotted oak borer
Gold-spotted oak borers, above, have killed tens of thousands of oak trees in five Southern California counties. Courtesy photo
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San Diego County forests threatened by invasive borer beetles

REGION — The California Board of Forestry and Fire Protection took steps Nov. 4 to limit the spread of invasive beetles in Southern California.

Specifically, the state agency is seeking to prevent further expansion of two species of beetles, shot-hole borers and gold-spotted oak borers, which have both contributed to the ongoing oak tree mortality across San Diego, Riverside and Orange counties.

“…The board is facilitating Cal Fire’s ability to enter into agreements in the newly established (infestation) zones with public and private landowners, as well as state and federal agencies, so they can partner to control or eradicate these invasive pests,” said Board Chair Keith Gilless. “The zones will also promote greater outreach and education about the risks of long-distance firewood and green waste movement as they relate to the spread of these pests to new locations.”

More than 100,000 mated females can emerge from a single tree capable of attacking and infesting other trees commonly found in riparian areas (near surface water), including California sycamore, cottonwood, willows and valley oaks.

These insects are known to cover long distances due to the movement of firewood and green waste materials.

Gold-spotted oak borers are currently found in five Southern California counties (San Diego, Los Angeles, Orange, Riverside and San Bernardino) where they have killed tens of thousands of susceptible oaks (mature coast live oak, canyon live oak and California black oak).

According to Cal Fire, tree mortality caused by these pests reduces property values and increases fire danger. Loss of oak diminishes habitats, threatening Native American traditional practices and wildlife species.

For more information, go to or To find out more about keeping firewood local to limit invasive species spread, go to