Walnut Twig Beetle

The Walnut Twig Beetle (Pityophthorus juglandis) is a tiny insect that is a major pest of black walnut trees (Juglans nigra) in North America. The adult beetles are about 2-3 mm in length, with a dark brown to black body and short antennae. They lay their eggs in small cracks and crevices on the bark of walnut trees, where the larvae tunnel into the cambium layer. As they feed and grow, they create galleries that can girdle the tree and cause wilting and eventual death. The first symptoms of walnut twig beetle infestation may include yellowing or wilting of leaves on one or more branches. In severe cases, the entire crown of the tree can die within a year of infestation. In addition to killing walnut trees, the walnut twig beetle is also a vector of the thousand cankers disease, which is caused by a fungal pathogen that infects the inner bark of the tree and can cause further decline and death. Walnut twig beetles are most commonly found in areas where walnut orchards or natural walnut forests are present, but they can also infest ornamental or landscape walnut trees. In order to prevent infestation, it is recommended to regularly inspect walnut trees for signs of beetle activity and to prune and destroy any infested branches as soon as they are detected. In addition, treatment with insecticides can be effective in controlling walnut twig beetles, especially when applied early in the infestation.