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Pest Impact

Losing Oak Trees Has Many Impacts

Goldspotted Oak Borer (GSOB) infestations have many impacts. Attacks affect the regional oak tree population, contributing to their death. All those who value oak trees, whether it be for cultural, environmental or aesthetic purposes, are impacted by the rise in oak tree mortality. Oaks play an important role in the culture of Native American tribes. A reduction in oak tree population threatens their cultural practices. Loss of oak trees reduces habitat and food supply to wildlife. Dead and dying oak trees create a more dangerous wildfire situation by adding combustible fuel and increasing safety hazards along evacuation routes. Containment of GSOB is necessary to prevent further and farther-reaching impacts.

How Oak Trees are Impacted

The Goldspotted Oak Borer (GSOB) leaves visible evidence on three species of oak trees common in San Diego County. When their larvae create feeding galleries underneath the surface of the bark, GSOB attacks may be recognized by the following evidence:

  • Red or black staining in dime-sized to half foot sections
  • Blistering and oozing on the surface of the tree
  • Crown thinning
  • Twig and branch die-back
  • Premature leaf loss

Evidence of injury can also include chipped outer bark from woodpeckers feeding on the larvae and small D-Shaped exit holes where the gold spotted beetles pupate and emerge from the tree. Impact varies between three oak species and can consist of gray or brown coloring in the crown of the tree and thinning of the foliage.

Felled GSOB Infested Oaks
More Information

If you recognize symptoms of GSOB or suspect local oak populations may be affected, please visit the following pages for more information.

What You Can Do


Photo Source: Lorin Lima, University of California Cooperative Extension (Bone Yard) and Tom Coleman, U.S. Forest Service Entomologist (Slideshow)