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...
- Author: Beatriz Nobua-Behrmann
- Posted by: Karey Windbiel-Rojas
When tiny tree-killing beetles first arrived in Southern California several years ago and began destroying urban and riparian forests, they raised widespread concerns among both tree experts and affected communities. More recently, invasive shothole borers have captured far less attention, and many people may think the pest threat is over. Unfortunately, it's not!
While significant progress has been achieved in invasive shothole borer research, surveying, trapping, and management programs, these beetles are still an ongoing threat to the state's urban and wildland trees. Continue reading to find out what you can do to be part of the solution to this invasive pest issue.
What are invasive shothole...
- Author: Beatriz Nobua-Behrmann
- Author: Randall Oliver
- Posted by: Elaine Lander
Two identical looking species of wood-boring beetles, collectively known as invasive shothole borers (ISHB), have killed thousands of trees in Southern California and pose an ongoing threat to California's urban and wildland forests. These beetles, which are not native to the United States, were first identified in Los Angeles County in 2012 and have since spread to six other counties: Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura.
Beetles, Fungus, and Impact
The polyphagous shothole borer (Euwallacea fornicatus) (Figure 1) and the Kuroshio shothole borer (Euwallacea kuroshio) are small ambrosia beetles that have a symbiotic relationship with several species...
- Author: Beatriz Nobua Behrmann
[Originally published in the Fall 2018 issue of the Green Bulletin. Modified slightly from original.]
Invasive wood-boring beetles are attacking hundreds of thousands of trees in southern California, including commercial avocados, and trees within urban landscapes and wildland environments.
The invasive shot hole borers (ISHBs) consist of two closely related and morphologically identical species of beetles in the genus Euwallacea: the polyphagous shot hole borer and the Kuroshio shot hole borer. Despite their small size (1.8–2.5 mm) (Figure 1), these beetles are causing big...
