Questions and Answers
Yellow crazy ants in the Northern Territory 
Questions and Answers
How do we think yellow crazy ants came to be at a residence in Berrimah?
From initial surveys of the infestation, it appears that the low density of yellow crazy ants at this site suggests that this is a fairly recent infestation, possibly within the last three years. If this is the case, eradication may be much more feasible; however a more in-depth survey is required to determine the extent of the invasion of yellow crazy ants in Darwin.
Are yellow crazy ants in any other locations in Australia?
Yellow crazy ants have also been detected in Queensland, on Christmas Island, and in Arnhem Land. There are currently programs to eradicate this pest species in each of these locations.
What is going to be used in an attempt to eradicate these crazy ants?
Once we know the extent of the distribution of yellow crazy ants, we will be in a better position to plan eradication of this species. However, other eradication programs have used ‘Presto® Ant Bait’ and/or ‘Campaign® Ant Bait’. A third product, ‘Distance® Ant Bait’ is also being trialled for eradication of yellow crazy ants.
How safe is the use of this poison in residential areas?
These chemicals pose a negligible risk to wildlife when used as directed (such as at the concentration that would be used to eradicate yellow crazy ants), and in other locations of use have not had any impact on reptiles, birds, mammals or humans. Nevertheless, every precaution will be taken to protect people, native wildlife and domestic animals throughout this program.
These poisons may be toxic to fish and aquatic invertebrates, and for this reason will not be used in proximity to open water.
What do yellow crazy ants look like?
Yellow crazy ants are a yellow-brownish colour, and measure approximately 4mm long. They have particularly long legs and antennae.
What damage do yellow crazy ants cause?
Yellow crazy ants have been associated with declines in native invertebrates and vertebrates. These declines are usually a result of competition or predation, as yellow crazy ants are either faster at locating food or they swarm over native animals because of their huge colony sizes.
In addition, research has shown that these ants also cause declines in seed dispersal, increased growth of sooty mould on trees and plants (which affects plant productivity), and reduced nutrient recycling in their introduced range.
On Christmas Island, yellow crazy ants have caused a significant reduction in populations of terrestrial red land crabs.
Do yellow crazy ants bite?
No. Yellow crazy ants spray formic acid on their competitors or prey. This causes these animal or insect to become very agitated because the formic acid causes blindness. The yellow crazy ants then swarm over the animal or insect. This formic acid has no effect on humans.
Why are yellow crazy ants so successful at invading a new area?
Yellow crazy ants are listed as one of the top 100 most invasive species worldwide. Some of the characteristics that make them so successful include:
- Very large population sizes. This enables them to overwhelm native insects and other animals, such as birds and lizards.
- They have many queens in their nest, making them difficult to manage because every queen must be eradicated for the colony to go extinct. If one queen fails to eat the poison, then the entire colony may survive.
- They eat a wide range of food, which means that they can access resources when other species may not be able to. It also means that they have lots of food available to them at all times.
- Yellow crazy ants are able to rapidly locate and recruit to food and water, meaning that they find it and remove it before other insects or animals.
- Yellow crazy ants are very aggressive to native invertebrates and vertebrates. Their large colony sizes overwhelm other species, usually resulting in native animals and insects retreating to avoid them.
- Slow moving crabs, snails, small reptiles, birds that can’t fly out of the nest but mostly the insect community are most at risk from yellow crazy ants.
- Often yellow crazy ant colonies show genetic similarities and as a result they do not show aggression towards other colonies. This enables them to develop ‘supercolonies’, which is essentially one very large colony made up of lots and lots of individual nests.
- Yellow crazy ants are very territorial and they will fight with any insect that enters their territory.
Why does it matter if yellow crazy ants are in Darwin?
Many invasive ants spread through human transportation, including in cargo, soil, pot plants, wood products, and baggage. A nest is able to remain undetected in small gaps or crevices, and can therefore be easily transferred to another location. Since many goods originate from Darwin and are shipped to people’s homes, and because people are continually moving to and from Darwin, the likelihood of this species spreading extensively throughout the Northern Territory from a population in Darwin is very high.
What can you do?
If you think that you have yellow crazy ants at your home, contact one of our Wildlife Officers on 8995 5036 to report this detection.
Alternatively, you can help us by collecting ants from your backyard using an ant collection kit available from the Northern Territory Government’s Wildlife Management Unit by telephoning 08 8995 5036.
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Each kit contains:
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We need to know the exact distribution of these ants in Darwin for several reasons:
- It will provide information about how widespread these ants are in Darwin.
- It will enable us to identify the best plan of attack to manage the crazy ant infestation.
- It will help us develop an eradication plan
- After eradication, we can use this information to make sure our eradication efforts have been successful.
