Red imported fire ant

fire ant nest image
Fire ant nest
red imported fire ant image
Red imported fire ant worker

Fire ants, or more accurately the red imported fire ant (Solenopsis invicta), are one of the world’s worst invasive pest ants. With their ability to spread rapidly, their aggressive nature and painful stings, they can decimate the native wildlife and impact human activities wherever they become established.

In Australia there have been a few incursions over the years, but the main site of infestation is in southeast Queensland. They were first identified at the Port of Brisbane and in Richlands in 2001, although they were believed to have arrived 20 years earlier. Such is the potential impact on the environment, economy and lifestyle, a combined Commonwealth, State and Territories management program has been in place to prevent their spread to other parts of Australia.

Currently there is a 10-year eradication program underway. With the control area covering Brisbane, west to the Lockyer Valley and south to the Scenic Rim and Gold Coast.  In addition to government efforts, the program also needs the assistance of businesses, professional pest managers and homeowners to help in the eradication program.

Here is all you need to know about fire ants, plus information on what you can do to help and what to do if you think you have fire ants…


Fire ants are relatively small and unusually come in a variety of sizes within the same nest. Workers can vary in size from 2 – 6 mm long.

They are a shiny red / brown colour and typically have a darker abdomen.

Fire ants build very distinctive nests. Although they can be hard to spot when small, large nests can contain several hundred thousand ants.  In heavily infested areas there can be as many as a thousand nests per hectare (easily 10 or more nests in your average lawn).

What do fire ant nests look like?

  • Dome-shaped mounds, which can look like loose soil
  • Up to 40cm high and 50cm in diameter
  • No obvious entry or exit holes
  • Often there are very few ants seen on the mound (except if you stand on it!)
  • If you happen to stand on a fire ant nest, the ants “erupt” from the nest like lava from a volcano!

Where are fire ant nests found?

  • Typically fire ants nest in lawns, pastures, unused cropping areas and along the sides of roads and pavements
  • Often the nests will be built next to a hard object – post, tree stump, pavement edging, etc.
  • Also keep an eye on any disturbed areas or landscaping materials (soils, mulch, plants pots)

In Australia, red imported fire ants are found over a large area of southeast Queensland, including Brisbane, west to the Lockyer Valley and south to the Scenic Rim and Gold Coast.

The government release the latest fire ant detections every couple of months.

Scientists have modelled the potential spread of fire ants and they could cover a large area of coastal Australia, especially the warmer areas of the east and west coast… thus the high level of concern and the government eradication program.

Fire ants can spread through their mating flights (the new kings and queens), with new queens able to fly a kilometre or so from the original nest to start a new colony.

Nests can also expand by a process of budding, whereby a secondary queen, some workers and some brood move away a short distance from the original nest to set up a new nest. Through this process, multiple nests can cover a large area creating a “super colony”.

In areas subject to flooding, fire ants can actually build “rafts” made up from worker ants and float on the surface of the water, transporting them to new nesting sites.

In many cases, fire ant spread is aided by human activity, particularly in the movement of soil and landscaping materials. Although landscaping businesses should have fire ant control programs in place, if you’re having soil, landscaping materials or plants brought onto your property, you should still check them for fire ants (but wear gloves!).

Fire ant bites, or more accurately stings, are painful, a bit like a bee sting. The ants will bite and then inject their sting from their abdomen.

A single sting is bad enough, but often a victim (human, pets and other animals) will experience numerous stings before realising they are being attacked. Often this occurs because they are standing or sitting on or near a nest. As a result of multiple stings, the victim can feel like their body is “on fire”!

The pain from the stings typically dies down in an hour or so, but a blister or pustule may develop, which can become itchy and may last a week or two.

Much like with bee stings, some victims can experience allergic reactions and in rare cases anaphylactic shock. If you start to swell rapidly at the bite site, feel faint or nauseous, or have difficulty breathing call for medical help immediately.

Otherwise treat stings with an icepack to relieve swelling and pain. Although the area should be washed, avoid bursting any blisters or pustules as this can cause secondary infections.


As fire ants are a category 1 restricted pest you are legally required to notify Biosecurity Queensland if you think you see them. You can either phone Biosecurity Queensland on 13 25 23 or complete the online yard check report form.

Use the identification tips (above) for fire ants and their nests. If you are still not sure you have fire ants, you will need to contact Biosecurity Queensland or your local pest control company.

If you have fire ants, you need to call Biosecurity Queensland on 13 25 23 or complete the online yard check report form. If you are going to do your own fire ant treatment, complete this form after you’ve carried out the treatment.

There are three options available to homeowners

  • Purchase fire ant bait, such as PestXpert Nest Kill Ant Bait, and carry out the treatment yourself, according to the process below
  • Call your local pest control company. However, you need to check they have completed the National Red Imported Fire Ant Eradication Program They will charge for this service and take care of all the reporting requirements. If you take this option, get a quote first as prices vary.
  • If you cannot do the treatment yourself, call Biosecurity Queensland and they will determine the best strategy. They provide a free service for high-risk areas / those in need free of charge, generally within 12 business days

Fire ants can be treated with special ant baits which are labelled for the control of fire ants – ALWAYS READ THE LABEL BEFORE USE.

PestXpert Nest Kill Ant Bait (available from Bunnings) is different to the other ant baits on the market:

  • It includes two different types of food granules and two different active ingredients, for maximum performance. This also means PestXpert Nest Kill can be used to treat a range of outdoor ants, not just fire ants.
  • PestXpert Nest Kill is manufactured by Sumitomo Chemical who provide the bulk of the fire ant bait to the Queensland government

Using the built-in shaker, PestXpert Nest Kill ant granules can be sprinkled on and around nests, and in areas where the ants are active.

As small nests are difficult to spot, it is often a good idea to spread ant bait over the whole yard as a precaution, to make sure you eliminate all nests that are present.

Typically, nests will be eliminated within 1-2 weeks, but if there is still activity 4-5 weeks after application, often due to an applying insufficient bait initially, it will be necessary to carry out a second treatment.

Important application tips:

  • Apply when the ants are active
    • Fire ant season runs from September to June (when the ants are active)
    • Avoid applying during hot temperatures
  • Don’t apply if the ground is wet of if rain is forecast
    • This makes the bait go soggy – and the ants don’t like it!
    • Don’t water the area until at least 24 hours after application to give the ants a chance to gather the bait
  • Keep children and pets away from the treatment area until all the bait has been taken

PestXpert Nest Kill Ant Bait is a granular ant bait consisting of two different food granules, each containing two different active ingredients.

If the bait is sprinkled in the areas where the fire ants are active, they quickly find the attractive bait granules and take them back to the nest.

Back in the nest the bait granules are “processed” – the food is given to all members of the nest, not just the workers, but also the larvae and most importantly the queen(s).

The two different active ingredients work together to ensure complete control. One active ingredient acts like a normal insecticide, killing the ants that it ingest it. It is slow acting as you want the bait to be pass around the nest before the ants realise it’s not good for them! The second active ingredient kills larvae and sterilises the queen, even at very low levels. This is a useful back up in case the larvae and queen(s) only eat a very small amount of bait. This second active ingredient effectively sterilises the colony and breaks the ant breeding cycle.

As long as the Nest Kill bait is applied as per the pack directions, there should be a big drop in ant activity in 1-3 days with colony elimination within 1-2 weeks.

If there is still activity 4-5 weeks after the initial application, a second application will be required as it means they didn’t eat enough bait first time around.


Nest Kill 500g pack image
Large 500g pack
PestXpert nest kill ant bait
Standard 150g pack