Pacific Pests, Pathogens and Weeds

View full fact sheet

Summary

• Worldwide distribution. In tropics and sub-tropics. Common on about 80 plant families, particularly fruit and forest trees, and herbaceous ornamentals, but also ferns, orchids and palms. Citrus and mango are the main hosts.  An important pest.
• Eggs laid under females. “Crawlers” disperse, settle - often along midribs - moult and feed on sap, with excess expelled as honeydew. Damage by feeding and by sooty moulds growing on honeydew excreta and blackening leaves.
• Natural enemies: parasitoid wasps, but ants interfere with control by wasps and ladybeetles.
• Spread by crawlers on wind, and in the nursery trade.
• Cultural control: check nursery plants are free of scales; prune infested branches; destroy ants (hot water).
• Chemical control: soap, white or horticultural oils; or synthetic pyrethroids for ant control.