Goldspotted oak borers are attacking trees in California

SAN DIEGO (FOX 5/KUSI) — An invasive beetle is laying its eggs in the nooks and crannies of oak tree bark in California, leading to an even deeper rooted issue.

Goldspotted oak borers, otherwise referred to as GSOBs, are targeting trees in the Golden State, even though they are native to Arizona and Northern Mexico.

According to forest entomologist Beth Kyre with the US Forest Service, there’s a reason the beetles have migrated. She said they more than likely arrived in California in the early 2000s by way of infested firewood.

“Beetles will spread naturally, but human-assisted dispersal in infested firewood is by far the dominant means of spread,” said Kyre. “Ensuring that firewood is sourced locally is incredibly important and is one of the most impactful ways the public can reduce the spread goldspotted oak borers.”

Female beetles lay eggs on susceptible oak trees throughout the summer. Beetle larvae will hatch from the eggs and bore through the outer bark into the living tissue of the tree, Kyre explained.

From there, the larvae will feed and grow within the cambial tissue of the trees through the summer, fall and winter, transforming into adult beetles that emerge in the spring. The cycle then begins all over again.

“The cambial tissue that the larvae live in and feed on is responsible for moving water and nutrients throughout the tree,” Kyre continued. “The larval feeding damages and/or kills that tissue and prevents the translocation of water from the roots up to the leaves, and products of photosynthesis from the leaves to the rest of the tree.”

How does this affect the environment? Well for starters, increased oak mortality also leads to increased fuel loads in a landscape regularly threatened by wildfires. Put simply, an abundance of dying oak trees could be dangerous amid a hot and dry wildfire season.

Additionally, Kyre said the loss of oaks on public, private and tribal lands in Southern California “has lead to significant economic, ecological, cultural and aesthetic losses to the region.”

The best tool available to reduce the spread of GSOBs is adhering to firewood guidelines and sourcing firewood locally, in other words, burn it where you buy it. Ensuring that firewood is sourced locally is incredibly important and is one of the most impactful ways the public can reduce the spread of these invasive beetles.

“Dontmovefirewood.org is an excellent resource for understanding the risk associated with the movement of firewood,” said Kyre.

Once GSOBs have entered an area, the removal of heavily infested trees combined with the chemical protection asymptomatic trees, or trees showing no signs of GSOB activity, can also help mitigate further spread.

More information on goldspotted oak borer management can be found here.

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