Oak-killing beetle found near Big Bear
Insect said to be responsible for destroying 25,000 trees since 2013
Martin Estacio
mestacio@vvdailypress.com
A tiny killer, responsible for the deaths of thousands of oak trees, has been discovered for just the second time in San Bernardino County.
The invasive pest, known as the goldspotted oak borer, or GSOB, was discovered last week by Cal Fire, U.S. Forest Service, and County officials, according to a multiple-agency statement released Thursday.
Personnel found the beetle while doing inspections on dead and dying California black oaks on private property in the unincorporated mountaintop community of Sugarloaf, near Big Bear City.
This would make the discovery just the second time GSOB has been found in the county, the first being in the Oak Glen area in 2018.
It is also the second infestation found in the San Bernardino National Forest since 2012, officials said.
"This find is a big deal. GSOB is a very destructive oak pest and as it kills oaks, people cut them down, sell them for firewood, and the pest is moved into new areas," said Dr. Mark Hoddle, biological control specialist, in an email.
Hoddle is also the Director of the University of California Riverside's Center for Invasive Species Research and has studied the insect.
Smaller than a penny with six orange spots on its wings, GSOB was thought to have been confined to San Diego County until being found in Idyllwild in 2012.
Officials with the California Department of Food and Agriculture first detected it in San Diego in 2004, where it is believed to have been introduced from infested firewood from southeastern Arizona.
The pest has been deemed responsible for killing 25,000 trees in both San Diego and Riverside counties as of 2013, according to a paper Hoddle co-authored.
The scientist said the beetle was particularly ruinous to Cleveland National Forest, where dead trees increased the risk of fire, limbs dropping and resulted in hiking trails being closed.
Another study acknowledged the difficulty in managing wood boring insects attacking large trees due to their "cryptic habits, complex and lengthy life cycles, hurdles involving early detection of infested trees" and the limited effectiveness of insecticides.
GSOB's known victims include California black oaks, coast live oaks and canyon live oaks.
According to fire officials, GSOB's spread can be reduced by keeping firewood local and not transporting it.
Signs of possible GSOB infestation include:
- D-shaped exit holes on the main stem
- Black or red staining on the main stem or larger branches
- Woodpeckers feeding on larvae under the bark
- Rarely seen adult beetles that are bullet shaped and 1 cm long, with orange spots
- Larvae which are longer at 2 cm, white and legless
For more information, visit www.GSOB.org.
Martin Estacio may be reached at MEstacio@VVDailyPress.com or at 760-955-5358. Follow him on Twitter @DP_mestacio.