Yellow Crazy Ant

Current situation

22 January 2020

NSW DPI and Local Land Services have been leading the response to yellow crazy ants in the Lismore region first discovered in May 2018. The infestation was restricted to two sites; the Lismore CBD and Terania Creek North of Lismore.

Following an exhaustive baiting program no yellow crazy ants have been found since March 2019 at either the CBD or Terania Creek locations.

Yellow crazy ants are highly invasive and can build super colonies and devastate local flora and fauna and impact on agricultural production and the horticultural industry. Yellow crazy ants, although not a direct threat to humans, are serious and classified as a

prohibited matter event under the Biosecurity Act 2015 as they are a serious environmental pest which pose a risk to our economy, environment and communities. The provisions of the Act include a duty to notify NSW DPI if you become aware of, or suspect the presence of yellow crazy ants.


Extensive surveillance has been conducted in the local area and the two known infestations have received extensive treatment. The treatment program was subject to strict conditions to ensure there is no “off target” damage.

The response team has put a lot of effort into locating specific nests within the CBD infestation and trained an odour detection dog to accurately locate any additional nests. Further surveillance was undertaken in the broader region to determine if the known sites were part of a larger infestation. To date this surveillance and community reporting has not found any additional nests.

We are working hard to stop the spread of Yellow Crazy Ant into NSW and we need your help.  Remember - the sooner we know about an infestation, the sooner we are able to put in place measures to contain and eradicate yellow crazy ant.

Moving soil and vegetation restrictions have now been lifted

Yellow crazy ants can be spread with the movement of plants and soil. While the ants themselves spread relatively slowly, it is critical that the community works hard to prevent these pests from spreading by hitchhiking on garden materials, soil and with people and their belongings

In 2018 NSW DPI introduced movement restrictions to help stop the spread of Yellow Crazy Ants. This movement restriction has now been removed because of the decreased risk from the ants.

We need your help

You can help stop the spread of Yellow Crazy Ants by:

  • Regularly inspect your property for any sign of unusual ants or nests and report any suspicious sightings immediately.
  • Do not disturb the ants or nests or try to treat the infestation yourself as the ants will likely move location.
  • Report suspicious sightings immediately: Tell us if you suspect the presence of yellow crazy ant, even if you are unsure or think we may already know about the infestation.

How to spot a Yellow Crazy Ant

Yellow Crazy Ant is recognised by their pale yellow body colour, unusually long legs and antennae. The name 'crazy ant’ is derived from their frantic movements and frequent changes in direction, especially when disturbed.

Yellow Crazy Ants form super colonies with several queens and once a super colony is established, it can expand rapidly, in some cases doubling in size in 12 months.

Yellow Crazy Ant


NSW DPI, Local Land Services and Council identified strategic areas to treat the ant colony using the following methods:

  • Ground searching
  • Educating the community to check for and report suspicious ants. Avoiding the further spread (eg. by moving soil) is essential.
  • In order to effectively eradicate the ant, NSW DPI and its partners applied bait in and around the Lismore CBD and directly treated known nests and immediate area around the nest.
  • Care was taken to ensure best practice application of the baits, following conditions approved by the Australian Pesticides and Veterinary Medicines Authority.
  • Expert advice was also sought from Biosecurity Queensland who have extensive experience in applying ant baits.
  • The best method for destroying YCA colonies is by using the broad-spectrum Granular insecticide, Fipronil.  This is more commonly used on ants including Yellow Crazy Ant.
  • The team applying the baits generally targeted vegetated areas so the baits would not be washed away. Hard surfaced areas were avoided however the baits were applied to surfaces where there were cracks that contain ed the product and prevented it from being washed away.

Fipronil is specifically designed to target invertebrate animals (animals without backbones)  This product has been tested extensively and there is no evidence that Fipronil is harmful to humans.

The application method used, and the low-strength formulation chosen, present very low risk to non-target species.

Fipronil is not well absorbed by plants and is broken down by sunlight.

As part of the permit conditions the baits were not be placed near waterways or storm water drains.


The yellow crazy ant (Anoplolepis gracilipes) is a highly invasive exotic pest that can build super colonies and seriously impact local fauna, agricultural production and ecosystems.

Unchecked, it poses a serious economic and environmental threat, so it is important that we prevent it taking hold in NSW.

Yellow crazy ants were found at various sites in Lismore CBD in May 2018. Ongoing surveillance by the NSW Department of Primary Industries and Local Land Services identified several smaller infestations in outlying areas which were treated.

NSW Department of Primary Industries undertook a targeted luring and baiting program to eradicate the ants, with follow up treatments to ensure all ants were removed. For more information, please visit

The exact source of the infestation is speculative and we may never know how yellow crazy ant came to Lismore.

Yellow crazy ant tends to walk rather than fly and are generally very slow in expanding their range by themselves.

However, they can hitchhike in organic materials, or on people’s belongings, resulting in the infestation spreading. This is why it is critical for people to be aware and check for yellow crazy ant before moving equipment and materials.

When they achieve great enough numbers they are known to kill small animals. Although they do not sting, they squirt formic acid into the eyes of the prey which blinds the animal and they starve. The ants also tend to sap sucking insects which impact vegetation. This can change the composition of the vegetation in native forests.

The Department of Primary Industries and Local Land Services surveillance plan had several elements:

  • Responding to community reports to identify suspect YCA,
  • Inspection and monitoring of high risk businesses,
  • Inspection of properties in key areas upstream of Lismore and in flood deposition areas downstream of Lismore.
  • Strategic sampling and luring program within 10km of Lismore

You can help stop the spread of yellow crazy ant by:

  • Regularly inspect your property for any sign of ants or nests.
  • Do not disturb the ants or nests or try to treat the infestation yourself as the ants will likely move location.
  • Report suspicious sightings immediately even if you are unsure or think we may already know about the infestation.

The ant nests are not obvious and are therefore hard to spot.  As such, we do not have pictures of the ant nests but the best place to look for Yellow Crazy Ant is on the trunks of trees because they harvest sap sucking insects in the trees.

The Yellow Crazy Ant can be identified as follows:

  • Yellow to brownish ant with body about 5mm long.
  • Abdomen is dark brown, sometimes striped.
  • Legs and antennae are very long.
  • Body is long and slender.
  • Walking style is erratic.
  • May spray formic acid when disturbed


Phone: Biosecurity Hotline 1800 680 244

In Person: To Local Lands Services

A sample or photo of the ant will help with identification.

Movement restrictions were in place, preventing the carrying of vegetative matter and soil within a 5km radius of the Lismore CBD. These movement restrictions were removed in December 2019 following a review of the risk.