This invasive beetle has killed tens of thousands of trees in Southern California. Now it’s in the Bay Area

An invasive species of beetle that has killed tens of thousands of healthy trees across Southern California has been detected in San Jose, posing a threat to over 65 species of trees in the area.

The shothole borer tunnels into trees, introducing a fungus that serves as food for the beetles, and prevents the trees from transporting water and nutrients, often killing them in the process, the Santa Clara County Division of Agriculture announced Friday.

Native to southeast Asia, the beetle was first found in Los Angeles in 2003 and is believed to have arrived via packaging materials. Agriculture officials and arborists have been fighting the epidemic for years in L.A., Orange, Riverside, San Bernardino, San Diego, Santa Barbara and Ventura counties.

“it is a significant threat to our urban forests,” said Rhonda Berry, the CEO of of Our City Forest, the San Jose nonprofit that’s been working to develop the urban canopy for 30 years.

It’s unclear when the beetle made its way to the Bay Area, or how widespread the infestation is, officials said — it’s possible the insects have been in San Jose for several years.

It could be too late to eradicate the species from San Jose. Researchers are trying to determine the extent of the infestation.

“We’re asking for the community’s help in identifying trees that have been attacked by invasive shothole borers, which will help us determine the extent of the infestation,” said Drew Raymond, Acting Agricultural Commissioner for the County of Santa Clara. “While we probably can’t get rid of the invasive shothole borer at this point, we can contain the infestation to protect as many of our trees as possible.”

No bigger than a sesame seed, the beetle is a particular menace as it can kill several types of trees, including the box elder, the California sycamore, valley oak, Japanese maple and American sweet gum.

To spot an infestation, look for tries that have dead or dying upper branches, or wet-staining, which can look like a dark oozing on the tree’s bark. Other signs include small entry and exit holes on trees that are perfectly round and roughly the size of the tip of a ballpoint pen, surrounded by boring dust and sugary buildup.

Those who see such signs on their trees are asked to contact the Division of Agriculture at scc.agriculture@cep.sccgov.org or 408-918-4610. Division biologists can help confirm whether the invasive insect is present.

Berry urged community members to be proactive in inspecting their trees, noting that 85% of the urban forest is maintained by individuals, rather than public entities.

“The only way to curb devastation of the urban forest is by community members checking out their trees,” she said.