Invasive beetle has so far destroyed over 80,000 oak trees in Southern California

RIVERSIDE, Calif. (KABC) – Who would have thought that something so small could be so devastating?

Still, entomologists continue to raise alarm about the gold-spotted oak borer, an invasive insect that some experts say has killed more than 80,000 oak trees across Southern California.

“It’s just fascinating that this insect has been around for 50 million years and has adapted so well to survive,” said Joelene Tamm, a doctoral student at UC Riverside whose specialty is the golden-spotted oak beetle.

“It’s very small, about the size of a grain of wild rice,” Tamm said. Researchers suspect the insects originated in Arizona and were probably brought to Southern California in a bundle or truckload of firewood.

“They spend most of their lives hidden under the bark of the oak. The larvae cause destruction that ultimately leads to the death of the tree.”

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

Removing dead oak trees is expected to cost the state millions of dollars. Tamm said removing a dead oak tree can cost between $3,000 and $12,000, depending on its size and difficulty in reaching it.

But given the risk of forest fires and the threat to public safety, felling dead oak trees is unavoidable.

“This winter alone, a tree fell on a person’s propane tank and missed the house by six inches,” Tamm said. “According to Caltrans, a tree fell on a moving car and there was another report of a woman being directly injured by a falling tree. So it’s all very different.”

Tamm said trees that are not yet infected can be treated with certain insecticides. Property owners should seek advice from certified arborists.

Apart from that, Tamm said, the most important thing we can do to stop the spread of the gold-spotted oak borer is to stop the transport of firewood.

“If we stop transporting firewood, we can stop the insect from spreading,” said Tamm, who acknowledged that the gold-spotted oak beetle can fly several kilometers over the course of its life, but that this is not the main route of transmission from tree to tree.

“If we restrict the transport of untreated wood, we have a chance of stopping or slowing the northward spread until we find another possible management control.”