Ireland

Vine weevil

Otiorynchus sulcatus

You can often spot these black, wingless, beetle-like creatures on the leaves of indoor and outdoor plants. The signature semi-circular-shaped notches along the sides of leaves, caused by adults as they feed, are another tell-tale sign of a vine weevil infestation. The pale cream-coloured larvae meanwhile feed on the roots of plants destroying the root system and causing them to wilt and die.
Both the adults and their larvae can be one of the most destructive pests to shrubs, small trees, garden and house plants. They can be a particular problem in pot grown plants and adults seem particularly keen to lay their eggs in peat based compost.
Adult vine weevils are 1cm in length and wingless. They're dull black with light-coloured patching running down their backs. Adults are mainly nocturnal and only feed at night. Adult vine weevils appear between March and April from the soil of indoor pots, and between May and June from outdoor pots and borders. After mating, each female lays between 500 to 1, 500 eggs into the soil around their favourite host plants. Eggs hatch ten-15 days later into white C-shaped larvae with brown heads, which begin feeding on roots, tubers, corms and the lower stems of susceptible plants. They grow to around 1.5cm in length. The larvae remain in the soil until they emerge as adults. Most adults will die in late autumn when cold weather sets in. Although those in houses can often survive into the next year. Overwintering larvae will feed on the deep roots in the soil and pupate around late April to early May.