Invasive insect continues its spread across SoCal, killing more than 80,000 oak trees so far

Rob McMillan Image
Thursday, May 30, 2024
Invasive bug continues its spread across SoCal, killing 80K oak trees
A small invasive insect has decimated thousands of oak trees across Southern California.

RIVERSIDE, Calif. (KABC) -- Who would think something so small could be so devastating?

Nevertheless, entomologists continue to sound the alarm about the goldspotted oak borer, an invasive insect that some experts believe has killed more than 80,000 oak trees across Southern California.

"It's just fascinating how this insect has been around for 50 million years, and it's just so adapted at surviving," said Joelene Tamm, a graduate student at UC Riverside whose specialty is the goldspotted oak borer.

"It's very small, about the size of a wild grain of rice," said Tamm, who said researchers speculate the insects originated in Arizona, and probably were brought to Southern California within a bundle or truckload of firewood.

"They spend most of their life hidden under the bark of the oak tree. The larva causes the destruction which ultimately lead to the tree's mortality."

Tamm estimates that back in 2013, there were about 20,000 to 30,000 oak trees in Southern California killed by the goldspotted oak borer. She said that number has now jumped to more than 80,000 dead oak trees as the invasive pest marches to the north.

Removing dead oak trees is expected to cost the state millions of dollars. Tamm said it can cost between $3,000 and $12,000 to remove a dead oak tree depending on its size and how difficult it is to reach.

But given the wildfire threat, as well as the threat to public safety, taking down dead oak trees is a necessity.

"Just this winter one tree fell on somebody's propane tank and just missed their house by six inches," Tamm said. "Caltrans had a tree fall down on somebody's car that was moving, and there was another report of a woman being injured directly from a falling tree, so it's all over the place."

Tamm said trees that aren't infected yet can be treated with certain insecticides. Property owners should consult with certified arborists for a professional opinion.

Other than that, Tamm said the main thing we can do to halt the spread of the goldspotted oak borer is to stop moving firewood.

"We can stop moving firewood which will help stop spreading the insect," said Tamm, who acknowledged the goldspotted oak borer can fly a few miles in its lifetime, but that's not the main way it spreads from tree to tree.

"If we limit the way we transport wood that's not treated then we have a chance to stop or slow the spread northward until we can find another potential management control."