About the Beetles
The Mediterranean oak borer (MOB) is an ambrosia beetle native to the Mediterranean region, including Europe, the Middle East, and North Africa, where it primarily attacks oak species. The first North American infestations of MOB were confirmed in valley oaks in Napa County, California in late 2019, followed by Lake and Sonoma Counties in early 2020, and Sacramento County in September 2020. MOB has since been found in Mendocino, Yolo, and El Dorado Counties.

Female beetles are light brown and 3 mm (1/8 inches) long.
MOB females can be separated from all other bark and ambrosia beetles in California by the pattern of bumps on the tip of the abdomen.



Beetles require 5-8 weeks to develop from egg to adult and can have two or more generations per year. In California mated females overwinter in the gallery system and emerge in late winter or spring when the temperature approaches 80° F.