Insects and Spiders - native

Non-pest woodborer on Dec 16, 2025

Originally reported as Mediterranean Oak Borer (Xyleborus monographus)

Submitter has sample
EDRR Status: Local expert notified

Description of specimen

White grubs about 1/8" diameter and 3/8" long in a fallen oak branch. There are many burrows throughout the branch.
I tried to bring a sample to the ODF site in Salem, but there's no way to reach anyone. I'm going to burn the remainder of the branch if I don't hear from someone soon
Ed Kelly
503-510-2330

Commentary

Avatar of commenter Hi Ed, thank you for the report. Based on pictures you sent me seperately, these are another type of woodboring beetle. One of the many that are commonly found in dead and dying oak trees and branches and are not a pest concern. Their tunneling can be differentiated in that they are wide and may be filled with "sawdust". Whereas MOB galleries are smaller, branched, and black stained. You can see signs and symptoms of MOB in this factsheet:https://tinyurl.com/MOB-oregon

Christine Buhl
Dec. 16, 2025, 3:24 p.m.

Location

There's a huge oak tree on my neighbor's property next to the Mill Creek. It overhangs my property. Last week, a large branch fell into my yard. When I was cutting it to discard, I discovered grubs had burrowed throughout the wood. I recently read about the Mediterranean Oak Borer and I'm concerned that the entire tree may be infested.

Expert Reviewer

Avatar of Reviewer

Christine Buhl
Oregon Dept. of Forestry

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