Goldspotted Oak Borer

AA_GSOB_montage_topBB_GSOBA: Dorsal view of an adult female goldspotted oak borer. | B: Feeding galleries of larvae underneath the bark.

The Goldspotted Oak Borer is a flat-headed borer that was originally found around the San Diego, California area. GSOB are currently known to attack three species of oak: coastal live, canyon live, and California black. Adult GSOB are usually 10mm in length and have bullet-shaped black bodies with gold spots on their sides. Oaks with a DBH of 18 inches or above are at the highest risk of dying from a GSOB infestation.


GSOB attacks can be recognized by extensive bark staining, which can appear as black regions or red blistering with sap oozing from under the bark. Adult exit holes signify previous GSOB attack. These emergence holes are D-shaped and about 1/8” in width. On coast live oak, the bark is frequently removed by woodpeckers as they forage for larvae and pupae; this reveals the deep red-colored outer bark that contrasts starkly with the gray exterior bark. The presence of the larvae and their galleries, the emergence holes, and the associated woodpecker damage all distinguish GSOB infestation from infection with Phytophthora ramorum, the pathogen that causes sudden oak death. The infestation of a tree eventually results in dieback of entire branches and tree mortality.

Info Source: Arborjet

Trees will recover from infestation and will be protected from Goldspotted Oak Borer after the effective treatment that Joe’s Tree Care offers. We have certified arborists that can help you keep your trees health! Call us today! 512-215-1551