CAL FIRE estimates that the Goldspotted Oak Borers, also known as GSOBs, have killed at least 200,000 oaks across the Southland.
"So, you can look up at the tree, and you see a lot of the tree has no leaves on it or very few leaves. It probably has like 60% crown loss, 70%," said Kim Corella, a forest pathologist with CAL FIRE. "So, once a tree has that much crown loss, the chance of it surviving is minimal because there's so much crown lost, the ability to take up water nutrients is minimized."
CAL FIRE has also discovered an area in Simi Valley that is infested and now has many dead oak trees. These dried out oaks and fallen branches are not only a loss of habitat but also adding fuel for wildfires.
"Oaks are a keystone species in the environment and provide a lot of habitat resources. They're good fire protection; they're ember catchers," said Corella. "So, when you have these insects attacking these large diameter trees, which the insect prefers, you lose that habitat and that fire protection."
The species is native to Arizona, and it's estimated that they've been in San Diego since the early '90s. But 2025 was the first time that the beetles were spotted as far north as Ventura County.
"Because there's not a continuous oak from Arizona to California, there's a Mojave Desert. So, people come camping all the time. They probably brought in firewood ... and it's probably infested," said Corella.
As beetles are inching more and more north, CAL FIRE advises not moving any piece of firewood outside of county lines or more than 5 to 10 miles maximum. They also recommend buying locally, as indicated on the label, but if it's not labeled, it needs to be heat-treated at140 degrees Fahrenheit for one hour.