There are several flatheaded boring beetles in California, however only a few are of particular concern. The goldspotted oak borer (GSOB), Agrilus auroguttatus, is a metallic wood-boring beetle that threatens our native trees. Since it was introduced to Southern California on contaminated firewood in the early 2000s, this pest has caused extensive damage to woodlands and native oaks.
What does the goldspotted oak borer look like?
Adult GSOB are 0.4 inch long and 0.08 inch wide with bullet-shaped bodies. They are black with an iridescent green sheen and six distinct gold spots on their back.
What damage does the goldspotted oak borer cause?
Goldspotted oak borers only attack oaks (Quercus spp.). They are particularly damaging to coast live oak and California black oak. Adult beetles lay eggs on host trees and the larvae bore into the wood, feeding on the tree's vascular tissue. The larvae feed on the tree until they pupate into adults and exit the tree, leaving D-shaped exit holes in the bark. Extensive GSOB feeding can girdle trees, disrupting water and nutrient uptake and eventually causing the tree to die.
What can you do about the goldspotted oak borer?
Don't move firewood! The most important way to prevent the spread of invasive wood borers like GSOB, is to buy firewood where you're going to burn it. If you live in an area of Southern California where GSOB is present, avoid planting susceptible trees. If you need to remove an infested tree, keep the cut wood away from healthy oaks and tarp or grind the wood to kill any larvae present. To report possible sightings, fill out the Goldspotted Oak Borer Symptoms Reporting Form at https://ucanr.edu/sites/gsobinfo/What_You_Can_Do/Report_GSOB_Symptoms/
- Author: Jeannette E. Warnert
The invasive beetle, goldspotted oak borer (GSOB), has been found in the mountain community of Sugarloaf near Big Bear in San Bernardino County, reported the Chino Champion. The detection causes concern for other nearby communities where oak trees are prized.
"It realistically should be treated like a quarantine situation," said Doug Yanega of the UC Riverside Department of Entomology. "All it takes is a few people who don't know any better or think the rules don't apply to them to infest new areas."
The Chino Hills area has nearly 4,000 oak trees in parks, landscaping and parkways, not including trees on private property and city open space.
"The goldspotted oak borer posts an unprecedented threat to native oaks in Southern California," said UC Cooperative Extension specialist Mark Hoddle, director of the the Center for Invasive Species Research at UC Riverside. "Hiking trails and campsites have been closed because of the risk of branches dropping from dead trees."
For more information about GSOB, see the UC Cooperative Extension GSOB website.
- Author: Maria Murrietta
- Contributor: Kim Corella
Beetle borers. They are very small and they cause a lot of damage to trees, including death.
These insects have not been found yet in our County but they are very close and we are especially concerned about the ISHB which can attack over 110 tree species. Many of these are native riparian species such as Sycamore, Cottonwood, Alder, Willows, Box Elders and this insect also attacks coast live oak and valley oaks.
Cal Fire, the City of San Luis Obispo and UC Ag and Natural Resources are offering a workshop to educate the public about these two serious pests. Early efforts and education are key in preventing an attack on a wide range of tree species in San Luis Obispo County.
Here is a message from Kim Corella of Cal Fire:
I am excited to announce that we are having an invasive shot hole borer (ISHB) and goldspotted oak borer (GSOB) workshop here in San Luis Obispo on May 9th from 9:30-2:30.
This workshop will address biology, identification, surveillance, and management of infested trees, downed wood, and firewood. We'll cover these topics in the classroom, then have a hands-on lab to learn how to identify signs of shot hole borer damage, set up a monitoring program, and sample trees.
$30.00 registration fee includes lunch, a ISHB Field Guide, and ISHB Demonstration Kit. Pre-registration is required. Click here to register.
We have applied for CEU's from the Department of Pesticide Regulation and the International Society for Arboriculture.
For more information on the training and to register, visit www.pshb.org.
Kim Corella, Forest Pest Specialist, Cal Fire
Thank you, Kim, for keeping us well-informed!
For more information on this pest, infestation zones, and ways you can help limit the spread, see the University of California Goldspotted Oak Borer web site and UC IPM Pest Notes: Goldspotted Oak Borer.
[Text taken from the original article “Exotic Pests Invade California Landscapes” by Mary Louise Flint]
- Author: Sonia Rios
The California Avocado Commission is joining forces with Kevin Turner, UC Cooperative Extension goldspotted oak borer (GSOB) program coordinator (http://ucanr.edu/sites/gsobinfo/) in producing and distributing a number of roadside signs to help control the movement of pest infested firewood.
They are asking for avocado grower's participation in areas that are susceptible to the GSOB and/or the Polyphagous Shot Hole Borer (PSHB). GSOB susceptible areas include oak woodlands and forests while PSHB environments include avocado groves. Some of these susceptible locations are primarily focused in the Fallbrook, Escondido, Valley Center, and Alpine areas. Eventually signs will be developed that will feature both the GSOB and the PSHB and discourage movement of oak and avocado wood.
The signs can go in a variety of frame designs. Most signs are 4' x 8'and are normally inserted into a redwood frame, but can be as simple as posts and a piece of exterior plywood onto which the thin aluminum sheet sign can be attached. The signs should be placed visibly along major roadways or busy streets.
If you would like to participate by permitting signs to be placed on your property along major streets, please contact:
Kevin Turner, GSOB Program Coordinator, UCCE/UCR