Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Red imported fire ant (363)

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  • Worldwide distribution. Not recorded from Pacific island countries. Present in Australia (under eradication). Among world's 100 worse invasive species.
  • Ground-nesting in sunny agriculture, forest, and grass lands, urban areas. More aggressive and painful sting than tropical fire ant.
  • Nests - mounds up to 40 cm, 30-50 cm diameter; entrance holes 5-10 m away. Eat seeds, other insects, smaller vertebrates and honeydew.
  • Direct damage: vegetable seeds, fruits, new shoots and roots (large annual costs in US and Australia); loss of biodiversity; indirectly by defending aphids, mealybugs, scales and whiteflies from natural enemies.
  • Queens, males and three types of workers: minor, major and intermediate. Nests mostly with 2 or more queens, Up to 500 colonies/ha and each colony 200-400,000. Some with single queens.
  • Tramp ant. Spread by queens leaving nest, nuptial flight then new site, or 'budding'; spread via horticultural trade.
  • Biosecurity: requires risk assessments, regulations preventing introduction, protocols in case of breaches, and ability to make rapid response. Pacific Ant Prevention Plan available (IUCN/SSC Invasive Specialist Group).
  • Natural enemies: several Pseudacteon species under study in USA.
  • Cultural control: hot water at 47°C kills ants; over 49°C kills plants.
  • Chemical control: use (i) stomach poisons (fipronil, Amdro®, borax), (ii) growth regulators (methoprene, pyriproxyfen), (iii) nerve poisons (bifenthrin, fipronil, imidacloprid). See (
Common Name

Red imported fire ant

Scientific Name

Solenopsis invicta

AUTHOR Grahame Jackson
Information from CABI (2017) Solenopsis invicta (red imported fire ant). Crop Protection Compendium (; and Pacific Invasive Ant Toolkit. (; and Solenopsis invicta. AntWiki. (; and AntWeb. (; and Solenopsis invicta (2018) Global Invasive Species Database. (; and from Gruber AM, et al. (2021) Predicting socio-economic and biodiversity impacts of invasive species: Red imported fire ant in the developing western Pacific. Ecological Management & Restoration 22(1): 89-99. ( Photos 1-6 Amy Carmichael (2005) Red imported fire ant (Solenopsis invicta). Queensland University of Technology. PaDIL - (

Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/185: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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