Invasive shothole borers: tiny but deadly

They may seem too tiny to do much damage to a mature, healthy tree, but invasive shothole borers (ISHB) are responsible for the deaths of tens of thousands of trees in Southern California. These beetles bore into trees and infect them with Fusarium dieback, a fungal disease that kills the trees. Many native California trees like California sycamore, valley oak, and arroyo willow can be killed when invasive shothole borers attack them.

While these pests are currently only found in Southern California, they could spread to many other parts of the state. Limiting the infestation will reduce their impact. Controlling the beetles is difficult but includes regular monitoring of trees to quickly identify sources of beetles, disposing of infested cut wood, and appropriate pesticide treatments.

What can you do to help?

  • Don't move firewood around the state. These beetles and other potentially damaging beetles are easily moved on cut wood. Buy it where you burn it.
  • Learn more about host trees, symptoms of infestation, and what to do.

UC IPM's new publication, Pest Notes: Invasive Shothole Borers is written by various state experts on this pest and contains everything you need to know about the beetle. Visit the UC IPM website for specific management recommendations, identification of the beetles, and lists of trees affected.