Look-alikes
In Northern California, two native ambrosia beetles in the genus Monarthrum also create black-colored galleries in oaks. Monarthrum galleries branch from a single point like a palm leaf and do not cross over neighboring galleries. These native beetles typically only attack trees that are already dead, dying, or diseased.
![Monathrum galleries. Photo by Curtis Ewing, CALFIRE. Monathrum galleries. Photo by Curtis Ewing, CALFIRE.](http://ucanr.edu/sites/mobpc/files/326758display.jpg)