Black Walnut Mortality in Colorado Caused by the Walnut Twig Beetle and Thousand Cankers Disease

Fig. 2. (B) Extensive tunneling in inner trunk bark caused by walnut twig beetle adults and larvae. Note the extensive discoloration surrounding galleries caused by Geosmithia.



Image from Plant Health Progress article:
Black Walnut Mortality in Colorado Caused by the Walnut Twig Beetle and Thousand Cankers Disease