Goldenspotted Oak Borer (GSOB)

Quick Summary

The goldspotted oak borer (Agrilus auroguttatus) is a flatheaded borer beetle that attacks oaks. It prefers read oak group, and mature trees, but has been found to attack other oaks and smaller trees.

Goldspotted Oak Borer (Agrilus auroguttatus)

What to look for:

D-shaped emergence holes in mature trees, on main stem and larger branches
Crown thinning and uniform pattern of dieback. Visible branch flagging may be cause by a different pest, but not typical of GSOB damage
Bark staining
Bark injury from woodpecker foraging for beetle larvae in wood
Tree may eventually die after several years of injury
Removing bark may reveal larval galleries with frass (insect excrement). Pockets of sap may accumulate near galleries

Goldspotted Oak Borer infestation

The current distribution map of this pest can be found here.

More Information and Resources:

UC IPM Pests in Gardens and Landscapes Goldspotted Oak Borer

UC ANR Goldspotted Oak Borer website

UC ANR IPM Identification Guide