Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

New Guinea flatworm (385)

Click/tap on images to enlarge
  • Worldwide distribution. In Oceania, in many Pacific island countries from lowlands to 3500 m. It predates slugs, snails, earthworms, insects. One of the worse 100 invasive pests.
  • Damage: a generalist; reduced local snail diversity where introduced to control giant African snails. A host of the rat lung worm.
  • Prefers moist disturbed areas - forests, plantations, orchards. Lives in leaf litter, under rocks, timber. Reproduces sexually. Up to 60 mm long, flat, tapering from middle with central stripe and pale belly.
  • Spread: mobile, and via domestic and international trade in plants.
  • Biosecurity: Countries free from the flatworm, (i) avoid introductions to control giant African snail and (ii) regulate movement of plants, soil and products likely to harbour flatworms, across national borders. Ensure plant introduction use soil-less compost or are bare-rooted cuttings. If soil necessary, enclose plant and soil in plastic bag and immerse in water, 43°C for 5 minutes. 
  • Cultural control: make baits enclosing snails in 2 mm nylon bags; kill flatworms using boiling water.
  • Chemical control: none recommended.
Common Name

New Guinea flatworm

Scientific Name

Platydemus manokwari

AUTHOR Graham Jackson
Information from CABI (2018) Platydemus manokwari (New Guinea flatworm). Invasive Species Compendium. (; and (including Photos 1&2) Platydemus manokwari. Wikipedia. (; and from Peer J (2015) Discovery in the US of the New Guinea flatworm, one of the worst known invasive species. ScienceDaily. (

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.

Copyright © 2022. All rights reserved.