Vine weevil is an insect pest that infests a wide range of ornamental plants and fruits, especially those grown in containers. Adult vine weevils eat leaves, and the grubs can damage underground roots and stems. .
This is one of the most common and devastating garden pests. The adult weevils eat plant leaves at night during spring and summer, but it is the grubs that cause the most damage over autumn and winter months when they feed on plant roots, causing wilting and often plant death. Plants growing in pots or other containers, outdoors or under cover, can be severely damaged by vine weevil grubs. Plants in the open ground are less susceptible, but grubs can kill strawberries, primulas, polyanthus, Sedum, Heuchera and young yew plants.
The adult beetles feed on the foliage of many herbaceous plants and shrubs, especially Rhododendron, evergreen Euonymus, Hydrangea, Epimedium, Bergenia, Primula and strawberry. You may see irregular-shaped notches in leaf margins during the summer
Control On mild spring or summer evenings inspect plants and walls by torchlight and pick off the adult weevils. Shake small shrubs over a tray and collect any adults that fall off. In greenhouses, look under pots or on the underside of staging benches where the beetles hide during the day .You can try to trap adults with sticky barriers, placed around pots or on greenhouse staging. Or trap them in rolled up corrugated paper or pieces of sacking where they will hide and you can destroy them.
Encourage natural enemies. Vine weevils and their grubs are eaten by a variety of predators such as birds, frogs, toads, shrews, hedgehogs and predatory ground beetles.
There are biological controls of the larvae as microscopic pathogenic nematode (Steinernema kraussei or Heterorhabditis megidis, . Both nematodes can also be applied to garden soil, but give poor results in dry or heavy soils. They work best in open potting composts, such as peat or coir. Nematodes can be used safely on all edible and ornamental plants and are available from suppliers of biological controls. Chemical control
Ornamental plants grown in containers can be treated with Scotts Bug Clear Ultra Vine Weevil Killer) or (Provado Vine Weevil Killer 2) as a liquid drench applied to the compost. These insecticides give protection against the grubs for 2-4 months although neither product can be used to treat edible plants or ornamental plants growing in open soil. Keep up your guard because stopping treatment after the apparent disappearance of the pest can allow numbers to build up again.