Exotic ants

Yellow crazy ant

Yellow crazy ant 

In the Northern Territory (NT), yellow crazy ants have been found in Darwin and Arnhem Land. 

Yellow crazy ants are yellow-brown and around 4mm long. They have long legs and antennae.

Yellow crazy ants spray formic acid on their competitors or prey, which causes agitation or blindness in the animal. The ants will then swarm over the animal or insect. This acid doesn't affect people.

Yellow crazy ants are successful at invading and surviving new territory due to all of the following:

  • large population sizes - this helps to swarm native insects and other animals such as birds and lizards
  • they have many queens in their nest - all queens must be killed for the colony to be destroyed
  • they eat a wide range of food
  • they are able to find and move to food and water quickly, often before other insects and animals
  • they are aggressive to native invertebrates and vertebrates
  • they will prey mostly on insects, but also on slow moving crabs, snails, small reptiles and birds that can't fly out of the nest
  • they are not territorial to other yellow ant colonies - they will join colonies to form super colonies
  • they are very territorial and will fight with any insect that enters their territory.


Yellow crazy ants have caused declines in native invertebrates and vertebrates numbers. These declines are usually from competition or predation. 

They are fast at finding food and will swarm over native animals to move them out of an area.

These ants also cause the following:

  • decline in the spread of seeds
  • increase sooty mould on trees and plants, which affects plant growth
  • reduce nutrient recycling.

Report yellow crazy ants

If you think that you have yellow crazy ants at your home, contact the Wildlife Use and Pest Animal Unit:

Phone: (08) 8995 5039
Email: wildlife.use@nt.gov.au

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Last updated: 14 June 2019

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