GSOB Update: May 2017

GSOB Confirmed in Del Dios and Mt. Israel

This beetle - the Gold Spotted Oak Borer, is a highly invasive, non-native flathead borer that kills oak trees.

San Diego County Ag has confirmed the presence of GSOB based on pictures submitted to them on Thursday May 11, 2017. So far, Clark Mahrdt and I have identified the oak killing beetle in two locations on the north end of Del Dios, as well the confirmed location on Mt Israel near Detwieler Road. Additionally, Conor Lenehan, RSF Fire, announced its presence on Mt. Israel at the Elfin Forest/Harmony Grove Town Council meeting last month. According to neighbors, GSOB may have arrived in Mt. Israel a few years ago, but we believe this to be a new problem in Del Dios, based on my examination the trunks of failing and dead oak trees for the last 3 years.

Please review the GSOB Identification Guide, especially page 5. When you first start looking at the trunk of a mature oak tree you will notice there are a lot of different shapes and sizes of holes in it. GSOB has a characteristic D-shaped hole in the bark, about the size of the lead of a #2 pencil. 

GSOB D Shaped Hole in Oak Zoom.jpg

Evidence of GSOB

GSOB has a characteristic D-shaped hole in the bark, about the size of the lead of a #2 pencil.

The first steps for limiting the spread of this infestation are 1: Alert the community that no oak wood should be moved in or out of our area and 2: Determine the extent of the problem – how many trees are effected and how they are grouped. According to the resources below, activities to contain the extent of the damage by GSOB include removing dead and dying trees effected with the beetle and using preventative treatment of unaffected or slightly affected trees in the vicinity.

We will need to work together and coordinate our efforts to be effective in stopping the spread of this pest in our area.

I will post again as I have more information to share.

Stacy McCline


Del Dios Habitat Protection League



Additional links, resources and video can be found in our original GSOB post.