05/28/2026
Stay informed on the rapid increase and spread of the Mediterranean Oak Borer! ⚠️
Mediterranean Oak Borer is an invasive Ambrosia Beetle. These insects were first discovered in the United States, right here in Napa County in 2019. Mediterranean Oak Borers are attacking healthy Oak trees, specifically Valley Oak, White Oak and Blue Oak species, in Marin County and surrounding counties. These small insects vectors in a fungal pathogen which plugs up the Oaks vascular tissue. They vector in the fungal pathogen and use it as a food source. The wood from the dead or diseased trees should not be repurposed as firewood! This will continue the spread of the disease into communities, counties and states that are yet infected!
Photo Credit: Christine Buhl, Oregon Department of Forestry