Tiny Invasive Beetles Killing Trees in the Santa Monica Mountains

Screen Shot 2021-02-25 at 7.31.20 PM.png

Los Angeles County Supervisor Sheila Kuehl’s office is warning local residents of a “grave threat to natural habitats in LA County that has the potential to disrupt ecosystems and supply chains alike—and is about the size of a sesame seed.”

The Invasive Shot Hole Borer Beetles (ISHB), native to Vietnam, are two closely related invasive pests known to infest 137 different  species of trees, including avocados, common landscaping and California native trees in both urban and wildland environments. The tiny, wingless, brown-colored beetles bore barely visible tunnels in the tree’s trunk and produce a fungus that cuts off the tree’s food, causing tree stress and death within five years.

The County Agricultural Commissioner and Resource Conservation District of the Santa Monica Mountains (RCDSMM) is collaborating to help residents learn to identify this threat and take appropriate steps to mitigate damage. They warn that, “If you live in the Santa Monica Mountains, these pests could be in your backyard.”

Rosi Dagit, senior conservation biologist with the RCDSMM, reported the invasive beetles are “quickly reaching epidemic proportions, destroying entire riparian areas and resulting in widespread environmental, economic, and aesthetic implications for the region.” The pests were first detected in the Santa Monica Mountains in 2016, and have been studied in the Topanga area.

Dr. Greg McPherson of the U.S. Forest Service stated in a video on the topic that the ISHB could create potential environmental chaos. “If we don’t do something now, there will be explosive growth and a crisis, and we’ll lose tremendous amounts of tree canopy. People will be shocked.”

A four part training session will be offered  (May 18-June 3) with experts from the University of California – Agriculture and Natural Resources Department demonstrating how to identify an infestation and collect valuable data for their study. For more information on the training or to RSVP, email Rachel Burnap at rburnap@gmail.com.