Initial insights into the recently established invasive Mediterranean oak borer (Xyleborus monographus) within a novel host, Quercus garryana, in the Willamette Valley, Oregon

Sunday, November 9, 2025

8:50 AM - 9:05 AM Pacific

Location: Oregon Convention Center, D139-140, OCC

Presenting Author(s)

AM

Allison Monroe

Oregon State University
Corvallis, Oregon

Co-Author(s)

CE

Curtis Ewing

CalFIRE
MR

Max Ragozzino

Oregon Department of Agriculture
Salem, Oregon
Christine Buhl

Entomologist
Oregon Department of Forestry
Salem, Oregon
DS

Dave Shaw

Oregon State University

Xyleborus monographus (Fabricius) (Coleoptera: Curculionidae: Scolytinae), the Mediterranean oak borer (MOB), is an ambrosia beetle native to the Euro-Mediterranean region, western Asia, and North Africa. Its recent introductions to California (2017) and Oregon (2019) have been linked to rapid mortality of seemingly healthy, mature (DBH > 30 cm) Quercus species, raising concern for both native and ornamental landscapes. Despite the scale of this emerging threat, little is known about the beetle’s phenology, behavior, or ecological impacts in North America. Over the past two years, we monitored X. monographus emergence from trap logs and infested wood across multiple Q. garryana trees in the Willamette Valley, Oregon. Here, we present preliminary emergence data and field observations of beetle activity, host condition, and colonization patterns. These findings represent some of the first detailed ecological notes on X. monographus in the Pacific Northwest and lay groundwork for future research into its behavior, host associations, and potential impact in both natural and ornamental oak settings.