Xylotrechus nauticus
Pest description and crop damage Coal-colored longhorn beetle (name refers to elongate antennae) with an elongated body and long legs. Grey or white 'W' or 'M' shaped bands are present on the elytra (wing covers). The larva is a large, roundheaded borer that attacks stressed, dying or dead hazelnut trees. It can be found in the scaffold branches or trunks of trees affected by eastern filbert blight but may also attack hazelnut trees that are stressed or dying for other reasons. The exit hole can be distinguished from that of Pacific flatheaded borer as it is much larger and oval, rather than "D" shaped.
Biology and life history Adults chew an opening into the bark for laying the eggs, often introducing disease organisms that cause the wood to break down. The larvae may feed for 1to 3 years, creating tunnels that wander beneath the bark and creating a white, splinter-like frass as they go. Adults emerge from oval emergence holes to mate.
Management-biological control
There are no known biological controls, but it is likely that certain parasitoid wasps would target larvae.
Management-cultural control
As this insect only attacks stressed or diseased trees its presence is a symptom of other problems with the orchard. Minimize tree stress through good orchard site selection, disease management, fertility practices and irrigation.