Acorn weevil

The acorn weevil (Curculio glandium) belongs to the Curculionidae family within the order Coleoptera. It is a highly specialized insect pest that targets oak trees, playing a critical role in the ecology of forests by significantly reducing the germination capacity of oak seeds. It is easily identified by its distinctive long snout, which is particularly long in females.

This insect primarily attacks the acorns of various oak species, including Quercus robur and Quercus petraea. While it is rarely observed on other nut-bearing trees like beech or chestnut, its impact on oak populations is profound. The ability to penetrate the hard outer shell of the acorn allows the pest to access the nutrient-rich interior that is essential for the tree's reproduction.

The biological cycle of the acorn weevil is closely synchronized with the phenology of the host tree. After overwintering as larvae deep within the soil, they pupate in the spring. Once the adult weevils emerge, they feed on oak leaves before mating. The female uses her snout to drill a hole into the developing acorn and deposits a single egg inside, where the larva will feed throughout the summer months.

The primary form of damage is the complete consumption of the acorn kernel by the developing larva. This results in the loss of seed viability. Affected acorns are often identified by the presence of a perfectly round exit hole, through which the mature larva leaves the fruit to burrow into the soil. Such infestations can destroy the vast majority of a season's acorn crop, hindering natural forest regeneration.

Management and protection strategies focus on both cultural and chemical control. Cultural practices, such as the rapid removal and destruction of fallen acorns, are vital to preventing the larvae from reaching the soil to overwinter. In nurseries or seed orchards, chemical intervention using systemic or contact insecticides during the adult flight period can be effective in lowering the population and protecting the developing seed crop.