Weevils

Many weevil species can affect pome and stone fruit but they are relatively uncommon in conventionally sprayed orchards in NSW. Weevils can be a significant problem in organic orchards and some weevil species are high-priority pests in export markets.

The most potentially damaging weevils are:

1. Apple weevil (Otiorhynchus cribricollis). Photo: iNaturalist Australia.
2. Eucalyptus weevil (Gonipterus scutellatus). Photo: William M. Ciesla, Forest Health Management International, Bugwood.org.
3. Fuller’s rose weevil (Asynonychus cervinus). Photo: NSW DPIRD.
4. Fruit tree root weevil (Leptopius robustus). Photo: Pest and Diseases Image Library, Bugwood.org.
5. Garden weevil (Phlyctinus callosus). Photo: Pest and Diseases Image Library, Bugwood.org.

Pest identification

Weevils are small beetles that have snouts, a set of antennae, a rounded thorax, 6 legs and are usually coloured dark brown to red–brown. Different weevil species can be distinguished by the markings on their back.

Damage

Weevils damage the fruit, leaves and roots of fruit trees. Feeding on fruit causes scarring, making it unsuitable for the fresh market. Weevils feeding on leaves deposit excreta around the stem end of the fruit, which results in downgrading. Some weevils cause partial or complete ringbarking on the fruit stalks, resulting in reduced fruit size or abortion. The Eucalyptus weevil is a quarantine pest that can contaminate export consignments.

Monitoring

Monitor for weevils from late October to late December, depending on the species. Weevil infestations tend to be localised to one area of the orchard and infestation is likely to recur in these areas. Trunk banding with a sticky coating, such as polybutenes and wax, or using a fibrous material can be a useful way to monitor for weevil activity.

Management

Cultural and physical: good orchard hygiene will prevent weevil populations from establishing. Carefully inspect any equipment, including ladders and bins being moved from one area of the orchard to another, and always work on clean blocks before moving to infested blocks. Weeds and rubbish on the orchard floor can act as hosts for weevils to lay eggs and provide an alternative feeding site. Maintaining a clean weed strip and having a mown inter-row will reduce the number of weevils in the orchard.

Biological: weevils can be eaten by small birds and preyed upon by parasitic wasps. Avoid using harmful pesticides to increase the population of parasitic wasps, which will help control the number of weevils in the orchard.

Chemical: refer to the APVMA PubCRIS database (https://portal.apvma.gov.au/pubcris) for registered controls.