Goldspotted Oak Borer

Help Stop the Spread!  Don't move oak firewood out of San Diego County!

The side view of a black insect with orange spots.Goldspotted Oak Borer Interagency Working Group of San Diego County  

Forest Service entomologist Tom Coleman has discovered that much of the decline in local native oak species is due to the feeding activity of an insect that has recently infested California, the gold-spotted oak borer. The feeding habits of the insect directly result in mortality to oaks.  Because of declines in the oak populations, and the potential for the oak borer to spread and infest a larger area, the Cleveland National Forest is suspending public wood permits until further notice.

The insect, which does not yet have an official common name but is tentatively being called the goldspotted oak borer, is among a group of boring insects called metallic woodborers, flatheaded borers, or jewel beetles.

In the course of field studies to determine the reason oak populations are declining, Coleman discovered that the oak borer may have been inadvertently introduced to the region or may have expanded its range from other parts of theUnited States or from as far south as Guatemala.  Prior to the discovery of the beetle, drought was thought be the cause of oak deaths.  As many as 70 percent of the oak trees in these areas are infested.  Evidence of insect attacks on oak trees can be seen by the presence of the insect under the bark, D-shaped exit holes in the bark,woodpecker foraging, and staining of bark on the trunk and larger branches of the trees.

The trunk of an oak tree that displays signs of insect damage.The Forest Service held meetings in October 2008 in the affected communities to inform the public about the oak borer and to provide advice on how to reduce or prevent oak borer attacks. Since then, numerous agencies have been working together to assess the oak borer’s biology, management, potential impacts, and assist with education and outreach.  Research efforts are directed at assessing the oak borer’s current distribution and life cycle in southern California, effective survey techniques, treatment options for high-value trees, factors enhancing tree susceptibility, and firewood management.  Additional research and information continues to be gathered to better understand this problem.

Local citizen awareness can help determine the locations of infestations in the county. If you suspect a GSOB infestation in local oak trees, report it!

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