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Tiny Pest Means Big Trouble for Oak Trees

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An invasive beetle found in local oak trees was likely brought to Orange County in firewood.

The tiny Goldspotted Oak Borer has killed tens of thousands of mature oak trees in San Diego County since it was first identified there in 2004. Recently, this destructive pest was found in the Weir Canyon area of the Irvine Ranch Natural Landmarks, and local agencies are working quickly to isolate the infestation and prevent a similar tragedy here in Orange County.

The beetle infestation was found in 56 mature oak trees in a remote area of Weir Canyon. Of those infested, 20 were cut down and removed due to heavy infestation. OC Parks is working with Irvine Ranch Conservancy to treat and preserve the health of the rest of the affected coast live oak trees. Both groups are also working with OCFA, University of California Cooperative Extension, and state and federal fire agencies to develop a response plan in case the Goldspotted Oak Borer is found again in Orange County.


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This beetle is native to southeastern Arizona, so how did it end up in Orange County? After the infestation in San Diego, Goldspotted Oak Borer (Agrilus aurogttatus) was also found in Riverside County in 2012. Scientists have determined that the beetle likely travels as larvae in firewood that is bought or harvested at an infested location and then transported to parks, homes and wilderness areas. When the little hitchhikers become adult beetles, they leave the firewood and make their way to nearby mature oak trees, laying eggs and spreading their population.

The main thing the community can do to help prevent the spread of this invasive pest is to not move firewood. Agencies are encouraging the public to “buy it where you burn it” – don’t take firewood from one location for use in another location. If you go camping, buy wood at the camping destination and use it there. If you have leftover wood from your camping trip, don’t bring it back home. This is an easy way to help stop the further spread of invasive beetles, and help keep native oak trees healthy.

Local, state and federal agencies will continue to monitor oak woodland areas to catch any other infestations. To learn more about the Goldspotted Oak Borer and what you can do to stop its spread, the University of California Cooperative Extension Division of Agriculture and Natural Resources has developed an educational website at www.gsob.org. If members of the public suspect a Goldspotted Oak Borer in their firewood, they can use this site to make a report.