Bondi Junction NSW, Australia
Fact Sheets
Big-headed ant (361)
Pacific Pests, Pathogens and Weeds
Pacific Pests, Pathogens and Weeds


  • Worldwide distribution. Common in Pacific island countries. Among world's 100 worse invasive species.
  • Nests under logs, stones, tree bark, leaf litter, and occasionally in houses. Prefers disturbed areas. Eat seeds, other insects, small lizards and birds, and honeydew. A scavenger. Once colonises established, biodiversity declines.
  • Direct damage to agriculture seeds and plant parts; indirectly by defending aphids, mealybugs, scales and whiteflies from natural enemies.
  • Queens mate inside colony. Workers are 'major' (big-headed soldiers) or 'minor' (much smaller workers) that rear the brood.
  • Tramp ant; spread by 'budding' - queens, workers and brood move to new sites. Spread with international 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).
  • 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 (

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