Two-spotted oak borer

The two-spotted oak borer (Agrilus biguttatus) is a wood-boring beetle belonging to the family Buprestidae (jewel beetles) within the order Coleoptera. It is recognized as a significant threat to oak forests across Europe, often acting as a primary driver of oak decline during periods of environmental stress.

The host range is predominantly restricted to oak species (Quercus), although it may occasionally infest European beech and chestnut. The beetle is particularly attracted to trees suffering from water stress, heat waves, or existing pathological damage, making these trees ideal targets for female oviposition.

The life cycle is typically univoltine, meaning one generation per year, though it can extend over two years in cooler regions. Adult beetles emerge in late spring or early summer. They lay eggs in the crevices of the bark, typically on the trunk. Upon hatching, the larvae burrow into the phloem and cambium layer to feed, constructing galleries that effectively girdle the host tree.

The damage caused by Agrilus biguttatus is severe, as the larval galleries disrupt the flow of water and nutrients within the tree. Symptoms include the yellowing and thinning of the crown, dieback of branches, and vertical cracking of the bark. Once a tree is heavily infested, it often dies within a few growing seasons if no action is taken.

• Implementation of prompt sanitary harvesting of infested trees.
• Removal and proper disposal of infested timber before adult emergence.
• Maintaining forest site conditions to improve tree vigor.
• Monitoring adult activity using specialized trapping systems.
• Promoting natural biological control through predatory insects and birds.