Vine weevil

Vine weevils are a common and widespread in gardens, feeding on a variety of plants, both indoors and outdoors. Plants cultivated in pots and containers, whether outdoors or under cover, are most likely to experience severe damage from vine weevil grubs. Plants growing directly in the ground are less likely to be severely affected.

Adult weevils consume leaves during spring and summer. However, the grubs (larvae) cause the most significant damage, feeding on plant roots during autumn and winter. This root feeding can lead to plant wilting and, ultimately, plant death. Adult vine weevils are primarily active after dark. During daylight hours, the beetles conceal themselves in leaf litter beneath host plants.

Vine weevil adults are beetles, which cause leaf notching: While the leaf damage from adults rarely kills plants, certain plants are frequently targeted for feeding, leading to characteristic irregular notches along the leaf margins. These include:

  • Rhododendron
  • Evergreen Euonymus
  • Hydrangea
  • Epimedium
  • Bergenia
  • Primula
  • Strawberry
  • Camellia
  • Azalea
  • Fuchsia
  • Heathers (including Erica, Calluna, Daboecia)
  • Hosta
  • Photinia

Weevil larvae are grubs, which cause root damage: This is where the most significant and often fatal damage occurs, particularly for plants grown in containers. The grubs feed on plant roots, which can cause wilting and plant death. Plants highly susceptible to grub damage include:

  • Plants in pots and containers (across almost all species)
  • Strawberries (in both containers and open ground)
  • Primula
  • Polyanthus
  • Sedum
  • Heuchera
  • Young yew plants
  • Cyclamen (grubs can bore into tubers)
  • Begonia (grubs can bore into tubers)
  • Cacti and succulents (grubs can bore into stem bases)
  • Alpines
  • Ferns

A fill list of susceptible plants can be found on this factsheet.

Identifying Vine Weevil Infestation

Indications of vine weevil presence include:

  • Vine weevil grub symptoms: Plants may wilt and die from autumn to spring due to root consumption by larvae. Container-grown plants are more vulnerable.
  • Presence of vine weevil grubs: Plump, C-shaped, legless white larvae with light brown heads, up to 10 mm (approximately 3/8 inches) long, can be found among plant roots.
Vine weevil pupae
  • Adult feeding symptoms: Irregular notches on leaf margins occur during summer. If damage is observed on privet, it may be attributed to the Privet weevil, Otiorhynchus crataegi. Larvae of this species typically do not cause noticeable damage to host plants in gardens.
  • Adult weevils: Beetles approximately 9 mm (about 5/16 inches) long, dull black with dirty yellow markings on their wing cases.
Adult vine weevil. Dark matt appearance and characteristic orange tufts of hair on the wing cases.

Managing Vine Weevil

Vine weevil is a prevalent insect in gardens. Continued monitoring is advisable, as populations can re-establish after apparent disappearance, posing a risk to susceptible plants.

  • Tolerate leaf damage caused by adult beetles.
  • Remove beetles by hand where feasible. Inspect plants and walls with a flashlight on mild spring or summer evenings and manually remove adult weevils. Shaking shrubs over a surface such as an upturned umbrella or newspaper can dislodge and collect additional beetles. In greenhouses, inspect under pots or on the underside of staging benches, where beetles hide during the day.
  • In greenhouses, adult weevils can be trapped using sticky barriers placed around pots or on staging.
  • Promote wildlife in the garden. Vine weevils and their grubs are consumed by various predators, including birds, frogs, toads, shrews, hedgehogs, and predatory ground and rove beetles.
  • Frequently inspect susceptible plants to enable early intervention before a damaging population develops. Look for notched leaves, particularly on thick-leaved evergreen plants like rhododendron, as an indicator of adult presence.
  • When repotting plants, remove as many larvae as possible from the root area and compost.

Biological Control Measures

Biological control for larvae is available using microscopic insect pathogenic nematodes. Several species and combinations are offered (Steinernema kraussei, Heterorhabditis megidis, H. bacteriophora, and S. feltiae). These are obtainable from biological control suppliers and in sachet formulations from some retail outlets. They are suitable for use in containers and in open ground. Nematodes have the potential to affect other organisms; therefore, they should be applied with care and only when a specific problem requires treatment.

For optimal results, apply in August or early September when soil or potting media temperatures are sufficient for nematode efficacy (Steinernema species: 5-20ºC; Heterorhabditus species: 12-20ºC) and before vine weevil grubs have grown to a size capable of causing severe damage. Nematodes may yield poor results in dry or heavy soils. They are most effective in lighter soils and open potting composts, such as peat or coir. Nematodes can be safely used on all edible and ornamental plants.

A trap containing nematodes (Steinernema carpocapsae) is available for controlling adult vine weevils. These traps should be placed on the ground below plants damaged by weevils during the summer. Adults enter the trap during the day and become infected by the nematodes.