Those white oaks around Marin might be in trouble, courtesy of an uninvited pest. The Mediterranean oak borer, a beetle about as tiny as they come, has been crawling into Novato, sparking concern among arborists and property owners alike. The bug's been boring into valley oaks since May 23, when it was first spotted, according to Marin County's website.
Marin's Agricultural Commissioner Joe Deviney didn't mince words about the unwelcome guest, stating, per Marin County's website, "It was only a matter of time for the presence of this invasive pest to be confirmed in our county." Previously, this beetle set up shop in Napa County in 2019 and has been enjoying a tour de force across nine counties. It's like an invasive rolling stone gathering no moss, but killing off some trees along the way.
The Marin office of the University of California Cooperative Extension (UCCE) and various state agencies are teaming up to tackle the issue, working on detection, education, and hopefully some control over these beetles. Their work is cut out for them, as the beetles are difficult to spot at 3 millimeters. However, their dining habits, boring into stressed trees and then feasting on fungus they cultivate, are a hardy survival strategy.
The beetles typically start with a tree's branches before moving to the trunk, leading to death by a thousand cuts, or in this case, borings. Homeowners are taking note: Monitoring the oak crowns for signs of the beetle is now part of the neighborhood watch. And with males that don't have wings, the females literally take flight and spread their family tree. Symptoms to watch for include a decline in leaf growth and general branch malaise; if you spot these, Marin authorities recommend contacting a certified arborist.
