Fire ants are dangerous, imported pests that could spread to large areas of Australia. Fire ants could severely damage the environment, our outdoor lifestyle, and the agriculture and tourism industries. They inflict a painful, fiery sting, which can, in rare cases, cause a severe acute allergic reaction (anaphylaxis).
First detected in the Brisbane area in February 2001, these South American ants pose a serious social, economic and environmental threat. Fire ants are a category 1 restricted pest under the Biosecurity Act 2014, so landholders must report suspected sightings of fire ants on their property to Biosecurity Queensland or they may face heavy fines.
The National Red Imported Fire Ant Eradication Program has made significant progress in eradicating fire ants from Australia. Surveillance is ongoing, and treatment and containment measures are continuing in areas of South East Queensland where the ants have been detected.
It is essential that you remain vigilant
Fire ants (Solenopsis invicta) are quite small (2-6mm) and come in an unusual variety of sizes within one nest. Their heads and bodies are coppery-brown and their abdomens are darker. They are aggressive, particularly near the nest, and can inflict painful stings.
It’s vital that you’re able to identify fire ants on your property.
Fire ant nests
Fire ant nests have no obvious entry or exit holes.
Nests often appear as dome-shaped mounds, but these mounds are not always easily identifiable. They can be up to 40cm high, but may also be flat and look like a small patch of disturbed soil. They are usually found in open areas such as lawns and pastures, and along roadsides and unused cropland.
Nests can also be found next to or under other objects on the ground, such as timber, logs, rocks, pavers or bricks. Look near pots or any areas of disturbed ground as well as:
- in pot plants on the ground
- in stores of topsoil, mulch and potting mixes
- under landscape materials (e.g. logs, stones)
- under timber or pallets on the ground
- adjacent to buildings and other structures
- in untidy or overgrown areas
- near areas of permanent water (e.g. the banks of dams, rivers, ponds, aquaculture containers)
- tufts of grass in open areas, where the soil is built up around the tufts.
Location of fire ants in Queensland
Genetic analysis shows there have been 6 different incursions of fire ants into Australia; 5 recorded in Queensland and 1 in Port Botany, New South Wales.
In Queensland, the first two incursions were discovered in 2001, one in the south western suburbs of Brisbane and the other at the Port of Brisbane. The third and fourth incursions were found in Yarwun, Central Queensland in 2006 and 2013. The fifth and most recent incursion was found at Brisbane Airport in 2015.
The Port Botany incursion was discovered in 2014 with the NSW Department of Primary Industries leading the eradication response. Biosecurity Queensland provided assistance in the initial response and provides ongoing scientific and operational support when required.
Both the Port of Brisbane and 2006 Yarwun incursions have been successfully eradicated and the 2013 Yarwun incursion is due to be declared eradicated in July 2016.
Spread from the initial Brisbane infestation has led to infestations around the greater Brisbane area, Ipswich, Logan and Redlands. Isolated infestations have also been found in Scenic Rim, Gold Coast and Lockyer Valley.
Fire ants pose a serious social, economic and environmental threat.
How fire ants spread
Fire ants spread naturally through mating flights and budding. A mated female (queen) can fly up to 2km, while a newly mated queen finds a suitable nesting site, sheds her wings and starts a new colony.
Humans can spread fire ants via:
- shipments of infested nursery stock, soil or other fire ant carriers
- materials and containers stored in fire ant biosecurity zones
- machinery that has been used to move soil.
To stop the spread of fire ants, the Queensland Government has implemented movement controls in certain parts of Queensland (fire ant biosecurity zones).
Where fire ants came from
Fire ants are from South America and are native to the floodplains of the Paraguay River in Brazil, Paraguay and northern Argentina. They entered the southern United States in the 1930s, probably in soil used as ship ballast, and have been spreading across the US ever since.
Fire ants would have been unknowingly imported into Brisbane, possibly up to 20 years ago. The pathway of entry into Brisbane is unknown, but was possibly in a shipping container from the US. They were first detected in the Brisbane area in February 2001.
We often use a combination of a baiting program & direct nest injecting for fire ants on targeted properties.
What chemicals are used in the fire ant baits?
Fire ant bait is made up of corn grit soaked in a mixture of soybean oil and an insect growth regulator (IGR) – either S-methoprene or pyriproxyfen. S-methoprene is widely used in mosquito control programs, and pyriproxyfen is commonly used in dog and cat flea collars.
How does the bait treatment work?
The bait is thinly distributed across backyards and garden areas as well as parklands and paddocks. Any foraging fire ants in the vicinity will collect the bait and take it back to the nest.
The IGR within the bait leads to the sterilisation of the queen ant, preventing her from producing any more worker ants. After the last adult workers have died of old age (approximately 3-4 months) the queen is effectively starved, and the nest will naturally die out.
The IGR also affects the reproductive ants by causing them to drop their wings and prevent them from being able to spread naturally through flight.
How much of each chemical is used?
On an average suburban residential block (approximately 500 m2) about 100 grams of bait will be used, which is around a half a teaspoon per metre2. As the corn grits consist of 0.5% insecticide, very little active ingredient is distributed.
How safe are these chemicals?
The bait treatment is not harmful to humans or animals, as it is specifically targeted at fire ants. After the baits are distributed, they rapidly break down in direct sunlight.
The baits are used according to the conditions prescribed on the relevant product labels and permits from the Australian Pesticides and Veterinary Medicines Authority APVMA; an Australian Government regulatory body) to ensure safety to humans, animals and the environment.
Are these chemicals safe during pregnancy?
Scientific testing does not indicate that these insecticides can cause birth defects. The way these baits are used pose no risk to pregnant women or their unborn babies. However, it is always important to minimise exposure to all chemicals during pregnancy.
What precautions do I need to take?
The fire ant bait treatments pose no risk to public health or the health of pets. No specific health precautions by householders are considered necessary. It is quite safe to walk on ground that has been treated with bait.
What should I do if my child swallows some bait?
Exposure to active chemical is likely to be very low, particularly after a day or more has passed since the bait was applied. As these chemicals are of very low toxicity, no adverse effects would be expected if any bait were to be swallowed. However, if you have any concerns, seek medical advice from your family doctor.
How is the bait distributed?
Our main method of distributing the bait on residential property is by foot – with a hand held spreader.
The method of bait distribution varies depending on the size of each property and accessibility.
Do I need to take any precautions after my property has been treated?
For treatment to have the best chance of success, you must not water, mow or disturb your lawn, gardens or paddocks for 24 to 48 hours to allow for foraging fire ants to collect the bait. The active ingredient in the bait breaks down in a matter of days.
Also be aware that restrictions apply to the movement of materials that could carry fire ants such as soil, mulch, animal manures, baled hay or straw, potted plants and turf.
How regularly is this treatment required?
Properties within the designated treatment area are required to be treated two or three times between the months of September to May (weather permitting). Repeated rounds of bait treatment may be required over consecutive years, to eradicate fire ants from your area.
Bait treatment is only conducted during the warmer months when the ants are actively foraging for food.
Why does my property require treatment if I don’t have fire ants?
The baiting program for fire ants operates on all properties in known fire ant areas or areas that may be at risk of becoming infested. Immature nests could be on your property and not visible until they mature.
Fire ant bait or direct nest injection treatment – how is the type of treatment determined?
All fire ant infestation is assessed to determine the most appropriate response, which is either a containment or eradication treatment activity. Eradication treatment is the planned broad scale multiple applications of fire ant bait, and containment involves a direct nest injection (DNI) with insecticide.
Upon site inspections, further assessment of infestation density, nest contents and land use can result in a combination of treatment activity being scheduled to best respond to the particular site and infestation findings.
What is involved in direct nest injection treatment?
High risk infestation is generally treated by direct nest injection (DNI) with insecticide which is a method that kills the ants within three to five days.
High risk infestation is infestation which presents either a public safety risk such as on sporting fields and schools; or infestation which poses a spread risk such as infestation on areas around the program’s outer operational boundary or in land use associated with product movement.
Lower risk infestation is also treated by direct nest injection, and can take up to 8 to 12 weeks for properties to receive this aggressive treatment. Direct nest injection work is scheduled according to the prioritisation of the risk.
Where infestation exists within the planned eradication treatment area (currently in the west, around Lockyer Valley, Scenic Rim, Somerset and Ipswich local government areas), and does not pose a risk to public safety or spread of fire ants, infestation may be more effectively treated with the multiple bait applications that occur during the warmer summer months (usually September to May).