Mealybugs

Mealybugs are oval, soft-bodied insects, typically a few millimetres long, coated in a powdery or cottony white wax that often extends into filaments around the body margin. Colonies cluster in protected sites such as leaf axils, under bark, in fruit clusters, and around root crowns.

Signs of infestation include the waxy masses themselves, sticky honeydew on foliage and fruit, black sooty mould growing on the honeydew, and ants actively tending colonies for the honeydew they produce.

Female mealybugs lay eggs in a protective waxy ovisac or give birth to live young, depending on species, and colonies can build up through several overlapping generations per year in warm climates. Young crawlers are the main mobile stage that disperses to new feeding sites and, on wind or via ants, to new plants.

Feeding removes sap and can distort growth, while honeydew and associated sooty mould reduce photosynthesis and fruit or crop quality. On some crops, mealybugs also transmit damaging plant viruses, adding to the direct feeding impact.

Host crops include grape, cassava, coffee, and cocoa, among many other perennial, tropical, and greenhouse crops.

Regular inspection of protected plant parts — leaf axils, stem crevices, fruit clusters, and root crowns — along with checking for honeydew, sooty mould, and ant activity, helps detect colonies before they build to damaging levels.

Mealybug management fits within integrated pest management, combining biological, cultural, and monitoring-based approaches.

• Conserve and, where suitable, augment natural enemies such as ladybird beetles and parasitoid wasps
• Manage ants that protect mealybug colonies from natural enemies
• Prune and remove heavily infested plant material where practical
• Inspect planting material and avoid moving infested stock between fields or greenhouses