Writings: With a backlog of thousands of untreated fire ant nests Biosecurity Queensland is throwing an expensive cocktail of chemicals at them: to improve the statistics rather than kill ants. Time for a Royal Commission.

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 The explosion of fire ant nests in Brisbane, Ipswich, Logan, Redland and Gold Coast cities and the Scenic Rim region are a direct result of Biosecurity Queensland’s much touted, but disastrous $411.4m, 2017-27 Fire Ant Program.  The program promised to increase the area it treated, starting at the western edge of the infestation in the Lockyer Valley and the Scenic Rim, then ‘rolling’ the treatment program eastward towards the infested cities in the east in subsequent years.   Two years into the program and Biosecurity Queensland has treated only a fraction of the western edge it had targeted and the fire ant infestations in the east exploded. In May 2019, Biosecurity Queensland was drowning in a backlog of 9,000 untreated nests reported by the public.  There are thousands more now. In a desperate attempt to reduce the statistics rather than the nests, Biosecurity Queensland is now sending out teams to treat individual nests with an expensive, chaotic cocktail of chemicals.

Treating individual nests was never part of the original National Red Imported Fire Ant Eradication Program approved by the Agriculture Ministers in 2001. The original plan was based on the best advice from the USA where scientists have been researching this pest for decades. The mainstay of the plan for an infestation that already covered many thousands of hectares, was repeated broadcast baiting with an insect growth regulator. Worker ants feed the bait to the queen and it makes her infertile. Biosecurity Queensland uses Admiral Advance with pyriproxyfen and s-methoprene as broadcast baits in south-east Queensland.

US scientists recommend treating individual nests ONLY where they pose a medical threat to people or animals or in very small areas of turf or ornamental gardens because even the vibrations from approaching footsteps can be enough to disturb a nest and cause it to split and spread. Worker ants can evacuate the entire colony in less than a minute along lateral tunnels that can extend twenty metres underground.  And if a nest is killed, it is likely to be invaded by  undetected and untreated neighbouring fire ant colonies.

In the very specific situations where individual nests need to be treated, US scientists recommend a ‘Two Step Method’: applying a broadcast bait around the nest first, then if the ants are still present after several days, applying a fast-acting insecticide. Or better still, wait for the bait to work.

Biosecurity Queensland does the exact opposite.  Biosecurity Queensland treats individual nests first and then might, secondly, apply a broadcast bait. Evidence from the USA shows that one of the main reasons why eradication attempts failed there was, in part, because of problems with treatment methods and a significant reason for fire ants continuing to spread in the USA is because of the improper use of pesticides.  No wonder Biosecurity Queensland’s program is a failure.

Treating individual fire ant nests has always been more about reducing the statistics than killing fire ants. In 2001, the  program director ignored the science and introduced the practice to speed up progress. A computer model showed it would take eleven years to eradicate fire ants at the rate the program was going and the program had only five years of funding.  However, the 2002 independent scientific review of the program said the fact that a horse pasture had to be treated three times with chlorpyrifos to have any effect, and even then, some nests survived, showed the practice did not work. But the practice continued and the program went from a scientifically sound ‘bait and wait’ approach to a ‘search and destroy’ one. The infestation in now covers 500,000ha: more than twelve times what it was in 2001.

Biosecurity Queensland started treating individual fire ant nests with chlorpyrifos, then with fipronil.  Biosecurity Queensland is now adding Advion Fire Ant Bait which contains indoxacarb, Amdro which contains hydramethylnon and Synergy Pro which contains both hydramethylnon and pyriproxyfen to its chaotic chemical cocktail of individual fire ant nest treatments.  These products cannot be applied to areas that are wet with rain or irrigation or soon will be after treatment. They are toxic to fish and invertebrate aquatic life so cannot be used near waterways or areas with run-off into waterways. And they should not be applied directly to human or animal food crops.

And individual nest treatments are much more expensive than broadcast baits because they are more labour intensive. Biosecurity Queensland has recruited more teams to do the work. And the chemicals are more expensive. Biosecurity Queensland says individual nest treatments are five times more expensive than broadcast baits, for example Advion costs around $600 for 10kgs and Amdro costs $138 for 450g.

Biosecurity Queensland is sending out teams to apply a single dose of these products to individual fire ant nests.  Field trials in the USA show that a single dose of indoxacarb or hydramethylnon kills over 50% of nests, but active nests still remain: likely because undetected colonies that would have been treated by broadcast baiting moved in, or because treated colonies can move and split into several nests before they become inactive.

And Biosecurity Queensland is not doing any follow-up surveillance to monitor the effectiveness of this campaign of individual nest treatments. Biosecurity Queensland is advising the public that treated mounds could still be active five weeks after a single treatment, and if so, THEY, the public, need to report them to Biosecurity Queensland: ironically, adding more nests to the thousands the public has reported but Biosecurity Queensland has not treated.

This gives considerable weight to the argument that the purpose of Biosecurity Queensland’s expensive, chaotic cocktail of individual fire ant nest treatments is more about reducing the number of untreated nests, rather than actually killing them. Which is what the Queensland Audit Office said in 2017. They said Biosecurity Queensland is more concerned with reporting outputs and activities; ie how many nests or hectare it has treated, rather than with reporting progress towards objectives: ie how many nests it has killed or hectares it has cleared of fire ants.

Time for a Royal Commission.


  • Managing Imported Fire Ants in Urban Areas. Texas Imported Fire Ant Research and Management Team. Bastiaan M. Drees and Charles L. Barr.
  • Speed and Efficacy and Delayed Toxicity Characteristics of Fast-Acting Fire Ant (Hymenoptera: Formicidae) Baits. David H. Oi and Faith M. Oi. Journal of Economic Entomology 99 (5) 1739-1748 (2006)

1st November 2019