The adult goldspotted oak borer (GSOB) Agrilus auroguttatus is a small, bullet-shaped beetle about 10mm (0.4 in.) long and has six golden yellow spots on its dark green forewings.
Mature larvae are white, legless, slender and about 18mm (0.75 in.) long with two pincher-like spines at the tip of the abdomen. Larvae feed under the bark on the trunk and larger branches.
Larval feeding kills patches and strips of cambium tissue beneath the bark which causes dark staining and sap flow. The larvae pupate in the outer bark and leave D-shaped exit holes about 1/8 in. wide when they emerge.
Pupae are found in the outer bark and resemble adults, but are commonly white in color.
See Pest Impact for more about evidence of goldspotted oak borer attack.