Alpine longhorn beetle

The Alpine longhorn beetle (Rosalia alpina) is a significant wood-boring insect belonging to the family Cerambycidae, order Coleoptera. Known for its striking appearance and long antennae, it is primarily regarded as a pest of old-growth deciduous trees, where its larvae develop within the inner layers of the wood.

The beetle typically attacks a range of deciduous hardwood species. Common hosts include the European beech, as well as elm, linden, hornbeam, willow, and various fruit trees such as walnut and pear. It shows a strong preference for trees that are already suffering from physiological stress, fungal decay, or mechanical injuries to the bark.

The biology of the species is characterized by a long development period. After eggs are deposited into bark crevices, the emerging larvae tunnel deep into the woody tissue. They consume the inner wood for a period typically lasting 2 to 4 years. Pupation takes place inside the wood, and the adults eventually emerge through distinct, oval-shaped exit holes, completing their life cycle.

The harm caused by this pest is mainly technical. By boring deep galleries throughout the trunk, larvae degrade the structural integrity and economic value of the timber. While they often target trees that are already declining, their activity accelerates the mortality of the host, facilitating the entry of fungi and other secondary pests that ultimately kill the tree.

Protection and management strategies focus on sanitation and preventative care:

• Systematic removal and destruction of severely infested and dead standing trees.
• Proper disposal of timber to avoid providing breeding sites near healthy plantations.
• Maintaining high tree vigor through appropriate silvicultural and horticultural practices.
• Monitoring for flight activity and exit holes in areas with high susceptibility to infestation.