Large fruit-tree bark beetle

The large fruit-tree bark beetle (Scolytus mali) is a destructive species of the Curculionidae family. It is a wood-boring insect that targets fruit trees, primarily invading the cambium layer. Unlike some other pests that target fruit or foliage, this beetle attacks the structural integrity and vascular system of the tree, often leading to irreversible damage.

This pest has a wide range of host plants within the Rosaceae family. It predominantly infests apple and pear trees but is also commonly found on plums, cherries, apricots, and peaches. It rarely attacks healthy, vigorous trees, preferring those already stressed by drought, poor soil conditions, or previous fungal infestations.

The life cycle begins with overwintering larvae beneath the bark. In spring, as temperatures rise, the larvae transform into pupae and then into adult beetles. The adults emerge through small circular holes in the bark. They engage in maturation feeding, which involves gnawing on the bases of leaves and buds, before mating and initiating new egg-laying galleries.

The damage caused by Scolytus mali is twofold. Adults feed on leaf stalks and buds, causing premature leaf drop. The primary destruction, however, is caused by the larvae, which create complex galleries that sever the phloem. This disrupts the tree's nutrient transport system, causing individual branches to wither and eventually resulting in the death of the entire tree.

• Implement strict sanitation by removing and burning infested branches or entire dead trees.
• Apply white latex paint or lime wash to tree trunks to deter egg-laying.
• Utilize pheromone or ethanol-based lures to monitor population levels.
• Maintain optimal tree health through proper fertilization and irrigation.
• Apply targeted insecticide treatments during the peak adult flight period in late spring.