Writings: Does Biosecurity Queensland’s practice of injecting insecticide into fire ant nests really kill them, or is this labour-intensive practice just another Queensland jobs creation program?

Biosecurity Queensland introduced the practice of injecting insecticide into all newly detected fire ant nests; almost from the beginning and against scientific advice. The fire ant infestation is now ten times worse than it was at the beginning as fire ants continue to spread and re-infest treated areas. Therefore, I commissioned an independent literature search on the effectiveness of the practice. The literature search arrived at the same advice Biosecurity Queensland was given in 2002. Treating individual nests can be appropriate in small, non-agricultural areas where the ants threaten human safety. Extreme care needs to be taken not to disturb a nest. Even footsteps approaching a nest are enough to make the whole colony re-locate in less than a minute. Injecting an insecticide into a nest rather than spreading it on the surface is more likely to disturb the nest and cause it to re-locate. Constant monitoring is necessary after the treatment. It is the most labour intensive and expensive method of treating fire ant nests. Biosecurity Queensland has no documented evidence on the effectiveness of the practice of injecting nests, no cost/benefit analysis comparing a combination insecticide/baiting program (which comes with considerable additional costs to agricultural producers) with the near 100% baiting program experts recommended in 2001. But there is a good chance this questionable, but labour intensive process is just another jobs creation program at a time of high unemployment in Queensland. 22nd January 2018 Update 14th May 2018 Biosecurity Queensland confirmed that fire ant program managers HAVE NOT provided the Australian Pesticides and Veterinary Medicines Authority with any evidence that injecting the insecticide fipronil directly into fire ant nests actually destroys the nests and does not just cause fire ant nests to split and spread.

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Injecting insecticide directly into fire ant nests is a controversial addition that Biosecurity Queensland made to the National Red Imported Fire Ant Eradication Program. It was never part of the original plan approved by the National Red Imported Fire Ant Consultative Committee in 2001 The plan, recommended by international fire ant experts Professor Bastiaan (Bart) M Drees and Dr Charles Barr both from Texas A&M and Dr Sanford Porter from the US Department of Agriculture, Agriculture Research Service in Florida, had three main elements:

  • baiting the whole area of the infestation four times a year for three years, preferably by air to cover all hard-to-get-to areas, with a low toxic, ant specific bait that workers feed to the queen. The bait makes the queen sterile and, over time, the nest collapses.
  • surveying the area around the infestation to confirm the boundaries of the infestation, and
  • implementing strict movement controls to prevent people carelessly or accidentally moving fire ants out of the infested area in loads of soil or mulch or potted plants.

The original plan had the potential to effectively contain and kill fire ants with minimal impact on our environment.

But by early 2002, just months after the program started in September 2001, the program Director added the practice of injecting an insecticide directly into all fire ant nests that were found. A computer model had predicted that a program of baiting would take eleven years to kill the last fire ant. The Director knew the Commonwealth and other States had signed up for only a five-year program.  Without any scientific evidence to support his decision, the Director instructed that all known active nests should be injected, in the ill-conceived hope that the practice would speed up the eradication of fire ants. He effectively turned a ‘bait and wait’ fire ant program into the ‘search and destroy’ program we have today. The fire ant infestation is now ten times worse than it was in 2002 as fire ants continue to spread and re-infest treated areas.

Professor Drees was also a member of two of the independent scientific review teams that assessed the program in 2002 and in 2004. In 2002, the review team opined that the practice of injecting insecticide directly into nests was likely to do more harm than good. They said pressure injections disturb the nest and can cause the colony to split and spread, effectively escaping the insecticide. They noted that a horse pasture had to be injected with diluted chlorpyrifos (a strong chemical) three times to have any effect and that a percentage of nests were surviving direct nest injection. The review team said there was no evidence the practice worked and that it was slow and labour intensive. The national Red Imported Fire Ant Consultative Committee agreed, saying that the program was now relying on injections instead of baiting. They said because of the addition of nest injections into the program, there was now no evidence that baiting alone, the standard treatment for the majority of the infestation, worked. And they criticised the Director for independently, and without consultation, making changes to the program.

Nevertheless, with no evidence that the practice kills fire ants and plenty of anecdotal evidence that the practice does indeed cause nests to split and spread, the controversial practice of injecting insecticide into all known active nests is now a well-established part of how Biosecurity Queensland runs the National Red Imported Fire Ant Eradication Program. 

Sixteen years and $400m of public money later, the fire ant infestation is over ten times what it was in 2002. Fire ants continue to spread and continue to re-infest areas that have been repeatedly treated with both insecticides and bait. No suburb where fire ants have been found has ever been declared free of them. Biosecurity Queensland does claims that fire ants have been eradicated from Yarwun near Gladstone, but has no evidence to support that claim.

To determine if this questionable practice of injecting all known fire ant nests with insecticide is a beneficial addition to the National Red Imported Fire Ant Program, or not, I commissioned an independent literature search on the practice of treating individual fire ant nests, including the practice of directly injecting fire ant nests with an insecticide.

The most relevant articles come from the USA where scientists have been researching this aggressive and invasive pest for many decades. The fire ant situation in the USA is different from that in Australia. Fire ants are now well-entrenched in the USA. The aims of fire ant programs in the USA are to contain the spread of the pest with movement controls to minimise the risk of people spreading fire ants in truck-loads of nursery stock and soil and to minimise the impact on people and live-stock by managing the impact of fire ant incursions. On the other hand, Australian governments have been attempting to eradicate fire ants for the past sixteen years and intend to continue trying for another ten years.

Eradication attempts in the USA failed, in part ‘by problems with treatment methods’ and a significant reason for fire ants continuing to spread in the USA is due to ‘improper pesticide applications.’  Therefore, I commissioned an independent literature search to assess Biosecurity Queensland’s practice of injecting insecticide into all known active fire ant nests.

Scientific literature from the USA gives the follow advice on treating individual fire ant nests:  

  • It can be appropriate under limited circumstances; ie when a small infestation threatens human well-being,
  • If care is taken not to disturb the nest in the process. Approaching footsteps can cause the colony to evacuate in less than a minute.
  • The most common method of treating individual nests is by applying an insecticide to the top of a nest. Injecting an insecticide into a fire ant nest is less common and more likely to disturb the nest.
  • Treated areas need to be constantly monitored.
  • It is the slowest, most labour intensive and most expensive method of treating fire ant nests.

When to treat individual fire ant mounds?

The mainstay of any fire ant program in the USA, and the most effective and least labour-intensive method for controlling fire ants, especially over areas of infestation that cover hundreds of hectares, is by broadcasting a bait that targets fire ant queens. The down-side of baiting is that it does not protect an area against re-invasions by ant colonies from surrounding land or by newly mated queens. Ant populations can fully recover within 12-18 months of the last bait treatment. Therefore, it is critical to re-bait infested areas.

US fire ant advisors do make recommendations for treating individual nests where the infestation poses a medical threat to people and animals in small areas of turf or other ornamental areas and non-agricultural areas with less than 20 mounds in an area of less than ½ hectare. Individual nest treatments have the benefit of selectively treating only the colonies treated and preserves desirable competitor ant species. On the down-side a treated nest is open to rapid re-invasion by other fire ants.

The practice of individual nest treatment and monitoring the effect is the most labour intensive, time consuming and hence the expensive way of managing a fire ant infestation.

How to treat individual fire ant nests?

Where it is appropriate to treat individual nests, US advice is to use the ‘Two Step Method’. Step one is to broadcast a bait around the infestation, then, after waiting several or more days, nuisance nests can be treated with a faster acting insecticide. Or better still, the US advice is just to wait for the bait to work.

The biggest issue with individual nest treatments, and well-known to Biosecurity Queensland at the time it introduced the practice, is the problem of disturbing nests and causing colonies to re-locate before the insecticide has any effect. Fire ant mounds can be 75cm in diameter, 69cm high above ground but extending another 6 meters beneath the surface. They also have lateral tunnels extending outwards an average 23 metres. However, when a colony is disturbed in any way, the entire colony can evacuate in less than one minute. Vibrations caused by approaching footsteps or pouring a drench onto a nest is enough to make the colony re-locate. A single surviving queen is capable of re-establishing a colony. And in areas where there are a lot of fire ant nests, the disturbance caused by treating the first nest can be enough to cause all the other nests to re-locate.

Because it is nearly impossible to locate all of the colonies in an area, it is important to monitor the site and to continue treating undesirable mounds as they appear, making it a labour and time expensive process.

The most common ways of treating individual fire ant nests in the USA is by applying a contact insecticides to the surface of a fire ant mound so as not to disturb it.  Contact insecticides are formulated as dusts, granules, granules drenched with water after application or liquid drenches.  To come into contact with the ants, they are best applied during the times of the year and times of the day when ants are close to the nest surface. The method can fail if the ants survive by foraging underground. It is also the least environmentally sound method because the treated surface can remain toxic for a long time.

Less common are contact insecticides formulated as injectable aerosols that come in containers to which an injection rod is attached. Also less common is the use of contact insecticides formulated as liquids which are applied by rodding the chemical deep into the mound. Injecting a liquid insecticide is Biosecurity Queensland’s method for treating individual fire ant nests.

Which contact insecticides to use for direct nest injection?

The three chemicals commonly used for individual fire ant nest treatments in the USA are chlorpyrifos, fipronil and the pyrethroid resmethrin.

All three products are registered for multiple uses in Australia. Chlorpyrifos was initially used by Biosecurity Queensland to inject directly into fire ant nests. It has since been replaced with fipronil, which is less environmentally toxic. However, resmethrin is even less toxic because it decomposes rapidly with exposure to air and light and leave less residue but is not used in Australia to treat red imported fire ants.

Biosecurity Queensland’s practice of injecting a contact insecticide into fire ant nests

The practice of directly injecting a contact insecticide into all newly detected fire ant nests, has become a significant part of how Biosecurity Queensland runs the National Red Imported Fire Ant Eradication Program.

During the cooler months of 2017, fire ant nests popped up in at least a dozen new housing estates in south-east Queensland, putting the safety of residents and their pets at risk. There is possibly an argument for injecting those nests to keep residents safe. However, if Biosecurity Queensland had applied stringent controls on the movement of fire ant carriers like soil and mulch, there is a good chance new housing estates might not now be infested.

Biosecurity Queensland’s description of its practice on the website ‘About the eradication program: treatment’ It is a reversal of the Two Step Method advised in the USA: Biosecurity Queensland injects first and baits second.

‘Fire ant nests are treated by direct nest injection of chemicals and is carried out by qualified pest management technicians. The process involves spearing a rod into the ground around the nest and flooding the nest and tunnels with insecticide. The nest is also lightly showered with the liquid treatment. The surrounding area is bait treated which involves spreading small pieces of corn soaked with an insect growth regulator across backyards and garden areas as well as parklands and paddocks.’

Biosecurity Queensland currently holds two permits from the Australian Pesticides and Veterinary Medicines Authority (APVMA) for the use of injectable products containing fipronil as their only active constituent for the use against red imported fire ants (PER14458 and 14770).

Advice in the US is to limit this practice to small areas of turf, ornamental gardens and non-agricultural areas. The APVMA permits allow Biosecurity Queensland to inject fire ant nests in areas of every conceivable land use:

  • Turfs and lawn, including residential lawns and ornamental garden beds.
  • Agricultural situations
  • Market gardens/intensive backyard and horticultural and vegetable gardens, and
  • Commercial, industrial, government utility and institutional areas.

The APVMA permits also allow Biosecurity Queensland to use the product in manners other than those specified on the approved label of the product.   So, apart from not treating nests when heavy rain is forecast to avoid contaminating waterways and avoiding bees, Biosecurity Queensland has pretty much open slather on how, where and when it injects fire ant nests.

But injecting fire ant nests in agricultural areas comes with significant additional costs to producers whose properties are treated this way: particularly those that are heavily infested.

  • Animals cannot be grazed on food stock cut from a treated area for 28 days after application.
  • Crops cannot be harvested from treated areas and crops from within one metre of a nest, or have come in contact with the insecticide must be destroyed.
  • Fruit from crops treated less than 6 months after application must be destroyed if the nest or treated areas is within one metre of any tree or vine, and
  • an area of crop surrounding each nest must be destroyed prior to treatment.

In agricultural areas, the Biosecurity Queensland has to bear the additional cost of testing the soil on treated agricultural sites, prior to them being re-planted.

Questions for Biosecurity Queensland on the effect of Direct Nest Injections

  • Given the process is contrary to recommendations from the USA to maximise baiting and minimise the use of insecticides, where is the documented evidence that the process is effective? And where is the documented evidence that the process does not cause fire ant nests to split and spread and made the infestation worse?
  • Where is the cost-benefit analysis that compares a combination baiting/insecticide fire ant treatment program with one which is closer to 100% baiting only: including the additional costs direct nest injections impose on agricultural producers?
  • Given the practice of injecting all newly detected nests is the most labour intensive and hence most expensive method of treating fire ants, is the practice just another jobs creation program for Queenslanders at a time of high unemployment in the State?

How the Queensland Government has benefited from the National Red Imported Fire Ant Eradication Program

The National Red Imported Fire Ant Eradication Program is funded under a cost-share arrangement between the Commonwealth, State and Territory governments. The Queensland government’s contribution is 10% of the $400m spent so far, But Biosecurity Queensland has been making 100% of the decisions on how that money is spent. In at least three instances, those decisions ignored scientific advice and used public money for the sole benefit of Queensland: at the expense of the public good.

In 2001, US fire ant experts advised quickly, cheaply and effectively baiting the whole fire ant infestation by air. But in 2001, the unemployment rate in Queensland was over 8%. So, the Queensland government mounted a large, expensive, slow and ineffective workforce to search for and kill fire ants. It wasted public money and fire ants spread.

By 2006, fire ants were re-infesting treated areas and continuing to spread. In an attempt to save the program and to keep Commonwealth money coming into the State, the Queensland government seized on the untried and untested remote-sensing technology to detect fire ant nests by helicopter. The independent scientific review panel of 2009 cautioned against it: saying it was likely to identify all sorts of warm things as nests and miss actual fire ant nest. Biosecurity Queensland went ahead anyway and the results were exactly as the science panel had predicted. Another huge waste of public money and the fire ant infestation tripled in size.

In 2002, against independent scientific advice, Biosecurity Queensland established the practice of directly injecting insecticide into fire nests. As fire ants spread and re-infest treated areas, there is no evidence that the practice works. But the practice is the most labour intensive and expensive method of treating fire ants and Queensland’s unemployment rate is currently around 6%. Is the Queensland government, yet again, using funding from the Commonwealth and other State and Territory governments to create another jobs program for unemployed people in Queensland?

The Commonwealth and State and Territory government have now committed another $400m of public money to the program over the next ten years.  If the Queensland government continues to make 100% of the decisions on how that money is spent, there is a good chance it will benefit the Queensland government at the expense of the public.


  • Allen, HR and Miller, DM. 2015. Field evaluations of broadcast, and individual mound treatments for Red Imported Fire Ant, Solenopsis invicta Buren, (Hymenoptera: Formicidae) Control in Virginia, USA. Sociobiology 62, 10-17.
  • ‘Control of the red imported fire ant’ from the Department of Entomology, North Carolina Cooperative Extension at North Carolina State University: available at https://www.ces.ncsu.edu/depts/ent/notes/Urban/pdf/rifa.pdf
  • Evans, CW 1988. US patent 4756118. Method and apparatus for the destruction of imported fire ants of the genus Solenopsis. https://www.google.com/patents/US4756118
  • Lemke, L. A., and J. B. Kissam. 1987. Evaluation of various insecticides and home remedies for control of individual red imported fire ant colonies. J. Entomol. Sci. 22: 275-281.
  • ‘Managing Imported Fire Ants in Urban Areas’: developed by the Texas Imported Fire Ant Research and Management Team. Current in December, this paper is in use in the fire ant infested southern states of the USA: Alabama, Arkansas, Florida, Georgia, Louisiana, Oklahoma, South Carolina, Tennessee and Texas. The lead authors are Prof Bastiaan (Bart) M Drees and Dr Charles L Barr who inspected the fire ant infestation in south-east Queensland in 2001. The paper is available at: http://extension.uga.edu/publications/detail.html?number=B1191
  • Moffett, D. 1994. US patent 5319878. Method and apparatus for extermination of imported fireant. https://patents.google.com/patent/US5319878A/en
  • ‘Red Imported Fire Ant Control’ by Hamilton Allen from the Virginia Department of Agriculture and Consumer Services: available at http://www.bedbuginfocenter.ento.vt.edu/rifacontrol.html