Tanner beetle

The Tanner beetle (Prionus coriarius) is a significant member of the longhorn beetle family (Cerambycidae). As one of the largest beetles in Europe, it plays an important role in the decomposition of wood, although it can be classified as a pest in certain silvicultural and orchard contexts when it attacks live or stressed trees.

This pest mainly targets broad-leaved trees, including oak, beech, birch, and alder. In some cases, it also infests fruit trees like apple and pear. It shows a strong preference for old, rotting, or weakened stumps and the subterranean parts of tree trunks, making detection difficult during the early stages of infestation.

The biological cycle of the Tanner beetle is relatively long, often spanning three to five years. Females deposit eggs near the base of trees or in the soil. The larvae, upon hatching, bore into the roots and the base of the trunk. They feed on the inner wood, systematically destroying the structural integrity and the sap-conducting tissues of the tree.

The damage caused by these beetles is characterized by extensive larval galleries packed with frass. This feeding activity leads to a decline in tree vigor, branch dieback, and eventually the death of the host tree. Because the damage is primarily located at the root level, the infestation is often only discovered once the tree's health has significantly deteriorated.

Effective management requires a proactive approach centered on sanitation and environmental maintenance. Key strategies include:

• Sanitary logging to remove infected or dying trees from the area.
• Complete removal of stumps to eliminate breeding grounds for the larvae.
• Promoting overall tree vitality through correct watering and nutrient management.
• Monitoring the population density of adults during the flight season to prevent further spread.