Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Cashew scale (383)

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  • Worldwide distribution. In Oceania, Australia, Fiji, French Polynesia, New Caledonia, and Vanuatu. Host range wide: Barringtonia, capsicum, chilli, citrus, coconut, coffee, mango, frangipani, Ficus, woody legumes.
  • Cover of female, semi-circular, 2.5-3 mm, domed, yellowish-brown, remains of first moult, clearly seen off-centre. Body of female, wine-red.
  • Damage: an important pest of citrus, cashew, cocoa.
  • Spread by 'crawlers' carried in wind, birds, clothing, machinery. Movement of nursery stock.
  • Natural enemies: ladybird beetle (New Caledonia, Vanuatu) and wasp parasitoid (New Caledonia).  
  • Chemical control: lime sulphur or wettable sulphur (follow manufacturers' instructions because of phytotoxicity concerns); alternatively, use insecticidal soap, white or horticultural oils. Note, avoid malathion and synthetic pyrethroids as they will destroy natural enemies.
Common Name

Cashew scale. It is also known as the trilobite scale.

Scientific Name

Pseudaonidia trilobitiformis. It was previously recorded as an Aspidiotus species, and as Pseudaonidia darutyi. [Note, a definitive identification of the scale on citrus from Fiji is awaited. The scale was provisionally identified using photos on orange. It is more usually found on leaves.]

AUTHORS Grahame Jackson & Mani Mua
Information from Diaspididae of the World 2.0 Pseudaonidia trilobitiformis. (; and from Garcia Morales G et al. (2016) ScaleNet: A literature-based model of scale insect biology and systematics. Database. ( Photo 3 MAF Plant Health & Environment Laboratory (2011) Trilobite Scale (Pseudaonidia trilobitiformis): PaDIL - (

Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/18: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Pacific Community.

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