Mealybugs

Mealybugs are sap-sucking insects that feed on a wide range of tree crops. They can shelter in the calyx of pome fruit and persimmons and are a pest of concern for export markets.

Pest identification

Female adult mealybugs are about 3 mm long, oval and usually covered in a white waxy coating. Males are usually small aphid-like winged insects. When squashed, mealybugs secrete a pale yellow liquid. Nymphs hatch from eggs within the female and are born live. They are small and orange-brown. Long-tailed mealybugs can be distinguished by their long tail filaments that can be as long as, or longer than, their body.

Damage

Mealybugs cause damage by inserting their mouthparts directly into the plants. Infested plant parts might be spotted, curled or wilted. Mealybugs also secrete a honeydew sap that encourages sooty mould growth, downgrading fruit quality. In severe infestations, tree health can be greatly reduced. Mealybugs can act as virus vectors and should be removed.

Monitoring

Monitor at least fortnightly during the growing season. Look in the calyx of the developing fruit weekly during harvest and record any mealybug presence. During dormancy, check under bark or other sheltered places for overwintering larvae or adults.
While monitoring for mealybugs, look for ant activity to determine if additional management measures are required. If ants are present, try to identify the location of their nests. Physically destroying ant nests in the orchard will reduce the number of ants that are protecting and spreading the mealybugs, rendering them more vulnerable to predation by beneficial insects.

Management

Cultural and physical: good orchard hygiene is critical for mealybug control. Infested material should be removed from the orchard and destroyed; do not use it as mulch. Mealybug infestations are worse on dusty trees, so avoid vehicle movement near trees on the windward side of infested blocks, and where possible, wet tracks down regularly.

Biological: a range of biological controls is available for mealybugs including various lady beetles, lacewings and specific parasitic wasps. Wasps can be extremely effective as they are highly mobile and efficient at seeking out their prey.

Chemical: refer to the Orchard plant protection guide for chemical suggestions.