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.
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
