Emerald ash borer

The emerald ash borer (Agrilus planipennis) is a wood-boring beetle from the order Coleoptera and the family Buprestidae. It is a highly destructive invasive species native to East Asia that has caused the decline and mortality of millions of ash trees (Fraxinus spp.) throughout North America and parts of Europe.

This pest exclusively attacks ash trees, thriving in both forest stands and urban plantings. Because the emerald ash borer has very few natural predators in newly invaded regions, its population can increase exponentially, leading to the near-total destruction of local ash populations if left unmanaged.

The biological cycle consists of egg, larval, pupal, and adult stages. Adult beetles typically emerge from trees in late spring, leaving characteristic D-shaped holes in the bark. Females lay eggs on the bark, and after hatching, the larvae bore into the tree and begin feeding on the cambium and phloem, creating serpentine galleries that effectively girdle the host.

The primary damage is caused by the larval feeding, which cuts off the tree's ability to transport water and nutrients. Infected trees often exhibit canopy thinning, epicormic sprouting (growth on the lower trunk), and longitudinal bark splits. Eventually, the tree loses its structural integrity and dies, usually within three to five years after initial infestation.

• Early detection using traps and visual surveys of canopy health.
• Removal and destruction of infested trees during the winter months.
• Systemic insecticide treatments, such as trunk injections, for high-value landscape trees.
• Biological control programs involving the release of non-native parasitic wasps.
• Regulatory measures to restrict the movement of firewood and nursery stock from infested areas.