An adult walnut twig beetle, Pityophthorus juglandis. A scanning electron micrograph showing the concentric arc patterns of surface roughenings (asperites) on top the head that help to distinguish this bark beetle species.

Photomicrograph with 1.00 mm scale.; Davis, Yolo Co. Credit: Andrew D. Graves
An adult walnut twig beetle, Pityophthorus juglandis. A scanning electron micrograph showing the concentric arc patterns of surface roughenings (asperites) on top the head that help to distinguish this bark beetle species. Credit: Andrew D. Graves