Foamy Bark Canker and Western Oak Bark Beetle (WOBB)

Quick Summary

The Western Oak Bark Beetle (WOBB) is a small (2mm long) beetle that spreads a fungus (Geosmithia pallida) when it bores into oak trees. Wet discoloration can be observed from the beetle entry holes, including foamy liquid down tree trunks.

Western Oak Bark Beetle, Pseudopityophthorus pubipennis

What to look for:

wet discoloration on trunk and primary branches
reddish sap exiting from entry holes after initial attack, followed by foamy, cream-colored liquid
attack on trees already stressed by drought, disease or other injuries

NOTE: these symptoms can appear similar to ISHB symptoms, but beetle holes are SMALLER

Western Oak Bark Beetle damage

The current distribution map of this pest can be found here.

More Information and Resources:

UC ANR Pests in the Urban Landscape blog. Foamy Bark Canker: A New Disease on Coast Live Oaks 9/25/2015

UCR Eskalen Lab Foamy Bark Canker Disease/Western Oak Bark Beetle

UCR Eskalen Lab Foamy Bark Canker + western Oak Bark Beetle Guide