SAN JOSE, CALIFORNIA — Invasive beetles the size of a sesame seed could pose a threat to trees across the region after their presence was confirmed in San Jose, officials said Friday.

According to the Santa Clara County Department of Agriculture, the invasive shotborer is a non-native species that affects more than 65 tree species in California. Researchers have found that the pests can kill at least 17 tree species, including ash-leaved maples, California sycamores and Japanese maples.

The shotborer spread in Southern California in the early 2000s, where authorities say the pests were responsible for the deaths of tens of thousands of trees. Although they have limited flight, they can travel on infested garbage, firewood or packaging materials.

The county isn’t sure how or when the tiny insects got to the South Bay or how widespread the infestation is. Agricultural researchers are working on monitoring methods to find out more. Officials said the beetles burrow into host trees and introduce a fungus that can cause diseases in trees that prevent them from properly using water and nutrients or even kill them.

While it’s likely impossible to eradicate the insects once they arrive, the county says there are some ways to reduce the threat, including first identifying potentially infested trees.

“We are asking the community for help in identifying trees that are infested with invasive shot borers. This will help us determine the extent of the infestation,” said Drew Raymond, the county’s deputy agriculture commissioner. “While we probably can’t get rid of the invasive shot borer at this time, we can contain the infestation to protect as many of our trees as possible.”

According to Raymond’s office, “perfectly round” entry or exit holes as small as the tip of a ballpoint pen are warning signs that a tree may be infested. The area around the holes may show signs of wet patches, resinous deposits, insect droppings, drilling dust or “sugary deposits.”

Anyone who suspects an infestation of trees on their property can contact the Agriculture Department at 408-918-4610, where biologists can assist with further identification. Property owners who need to remove or dispose of infested trees should refrain from throwing them away without first contacting an arborist.

For more information on the invasive shothole borer, contact the Statewide Integrated Pest Management Program.