- 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.
Pacific Pests, Pathogens, Weeds & Pesticides
Cashew scale (383)
Photo 2. Enlargement of Photo1 showing sub-circular female cashew scales, Pseudaonidia trilobitiformis, and the off-centre skin of the earlier moult.
Cashew scale. It is also known as the trilobite scale.
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. (https://diaspididae.linnaeus.naturalis.nl/linnaeus_ng/app/views/species/nsr_taxon.php?id=113125&cat=TAB_DESCRIPTION&epi=155); and from Garcia Morales G et al. (2016) ScaleNet: A literature-based model of scale insect biology and systematics. Database. (http://scalenet.info/catalogue/Pseudaonidia%20trilobitiformis/). Photo 3 MAF Plant Health & Environment Laboratory (2011) Trilobite Scale (Pseudaonidia trilobitiformis): PaDIL - (http://www.padil.gov.au).
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.