Fire Ants are Our Problem Too
Fire ants (Solenopsis invicta) are quite small (2-6 mm) as is shown by the life size photo with one identifying feature being that they have a range of sizes within each nest.
Their head and body is coppery-brown with a darker abdomen. They are very aggressive especially near their nest and will attack ‘anything’ that touches their nest, be it an animal, human or even a fallen branch.
Fire ants are natives of South America & entered southern United States in the 1930’s probably in soil as ships ballast.
It is now out of control with up to one third of the USA infested and little chance of ever eradicating the problem as it has become too widespread to eradicate.
Not only that it prevents people from using their backyard, sports ground, garden, small crop farm, etc and would be devastating if Australia were to become affected in the same manner.
As of July 1 2016, under the Biosecurity Act 2014, Fire ants are a category 1 restricted pest & you are required by law to notify Biosecurity Queensland if you think you see them anywhere or find them in your backyard.
In NSW it is the Department of Primary Industries & in Victoria it is the Department of Environment, Land, Water & Planning.
Picture showing original location of fire ants in South America
If possible, you should not try to eradicate them yourself, as this may inadvertently lead to spreading them further.Better to call in the experts.
To see if you are within a Queensland Biosecurity Zone go to:- https://www.daf.qld.gov.au/plants/weeds-pest-animals-ants/invasive-ants/fire-ants/restricted-areas/restricted-area-maps There are 3 Fire ant Biosecurity zones in Queensland.
Genetic analysis has shown there have been 6 different attacks by Fire ants in Queensland. The first discovery was in 2001 when a gardener at the Port of Brisbane was stung, became unconscious and was taken to hospital. An Entomologist then discovered that this was the first KNOWN Fire ant colony.
Additional colonies were also found in Yarwin, Central Queensland, in 2006 & 2013. The 2006 colonies have been eradicated with the 2nd one expected to also be eradicated by July 2016.
Another colony was found at the Brisbane Airport in 2015.
The initial infestation spread to Ipswich, Logan, Redlands, the Scenic Rim, Gold Coast & the Lockyer Valley (A major Salad bowl area), with a colony also found in Port Botany, NSW in 2014.
It is thought that Fire ants were unknowingly imported into Brisbane up to 20 years ago.
By James Wetterer – Sociobiology, CC BY 3.0,
Most Fire ant nests do NOT have any obvious nest, often being just a bit of soil built up around a tuft of grass, so are easily missed and transported to new places (eg at a Flea markets or Fetes) in topsoil, mulches or potting mix.
It is for this reason that you must check which zone you are in before you ever move soil or mulch or anything from your garden to another garden or area.
Check the map link to find out if you are in a fire ant zone.
Fire ants are spread naturally during mating flights where the mated Queen can fly up to 2 km before finding a suitable nesting site.
They can significantly affect the Agricultural industry by attacking newborn or hatching animals, either killing them or damaging them enough to make them so weak they are less able to get around to collect food. Hence they feed excessively in a smaller area depleting the food source which leads to starvation.
Crop farm infestations make it well nigh impossible to farm an area due to the chance of being stung by a fire ant if you disturb their nest. This leads to loss of viable farming country and loss of income.
Picture of queen and workers during a nuptial fight
By I, Lamiot, CC BY 2.5,
Additionally, Fire ants can prevent animals reaching water without the animals being stung at all. They are aggressive feeders on small ground fauna including insects, spiders, lizards, frogs, birds, & mammals, so they quickly displace or eliminate some of our unique native ground fauna.
This has been shown to occur in Brisbane when detailed observations were made comparing fire ant infested areas versus clean areas with the same range of species.
If a person (or animal) disturbs a Fire ant nest, a LOT of workers swarm out of the nest and attack the object. There are often 100s of workers attacking at one time, each usually stinging up to 6 times. ie 200 ants stinging 6 times means 1200 stings are inflicted within a few minutes on the unsuspecting object.
The sting causes a painful, burning, itching sensation which tends to last for at least an hour. Multiple stings give the sensation that the body is on fire.
After a few hours or even a day or two, small blisters form at the sting sites.
Theses often become itchy, taking up to 10 days to heal with a high risk of secondary infection if the blisters or pustules break.
There is no other known toxin quite like that of a fire ant in Australia, so if you happen to be allergic to them you will get a violent reaction to the stings, and you won’t know this until you have actually been bitten.
In USA up to 200 people have died from a severe allergic reaction to Fire ant venom.
Today’s Did You Know…?
Some people try to kill the Fire ant nests by tipping petrol, or kerosene, into it and setting it alight.
This is NOT a good idea as only the top part of the nest is destroyed with all the worker ants within it.
BUT the Queen ant may be hidden further below than where the petrol reaches and is not killed so her worker’s either take her to a new site (which the Fire ant control people then do not know where it is) or look after her until she produces more eggs that then develop into workers.
In Australia (which leads the world in Fire ant eradication) the nest site is spread with a food that is mixed with a slow acting ant poison.
The object is to kill, or sterilise the Queen so she doesn’t produce more Worker ants to take over from the Worker ants that die.
A Worker ant has a life of only 6 weeks. This means that as the colony dies there are no Worker ants to look after the Queen and no more Worker ants to forage for food, or protect the Queen & the nest.
Remember to call in the experts if you find a Fire ant nest anywhere so you can be sure you don’t spread them.
A video on fire ants in Queensland
Searching the fire ants nests from the air
My favourite – a fascinating look at fire ants devouring a part of a worm with an interesting commentary on fire ant behaviour.