Cossonus incisus

Systematic position. Cossonus incisus is a species of beetle belonging to the family Curculionidae (true weevils) and the subfamily Cossoninae. These insects are well-adapted to life beneath the bark of trees, playing a specific role in forest ecosystems where they often target weakened, diseased, or decaying deciduous wood.

Host plants and damage. The pest primarily targets broad-leaved trees such as poplar and willow species. Both adults and larvae cause damage to the cambium and phloem layers. By creating elaborate galleries under the bark, the beetles interrupt the tree’s nutrient transportation system, leading to wilting, thinning of the canopy, and reduced vitality of the host tree.

Biology and lifecycle. The lifecycle of this weevil is tightly bound to the host tree's condition. Females oviposit into bark fissures or damaged areas. The larvae live and feed in the inner bark and sapwood, undergoing several instars. Pupation usually takes place in the wood galleries, after which the emerging adults bore their way out, creating characteristic exit holes in the bark surface.

Pest significance. Cossonus incisus can be highly destructive in plantations and nurseries. Because the larvae feed internally, infestations are often difficult to detect until the tree shows clear signs of decline. The destruction of the cambium layer effectively girdles the tree, which can lead to total tree mortality in younger or already stressed saplings.

Control measures. Integrated pest management (IPM) is essential. The primary strategy involves rigorous sanitation, including the prompt removal and destruction of infested timber to disrupt the insect's breeding cycle. Maintaining tree health through proper fertilization, adequate watering, and preventing physical wounds significantly reduces the risk of infestation by this and other wood-boring pests.