Fire Ants - What are they?

Fire Ants, Solenopsis invicta, are serious pests which have been detected in Queensland, Australia. They inflict a painful sting and if not eradicated will seriously affect our lifestyle. They are the greatest ecological threat to Australia since the introduction of the rabbit and are potentially worse than the cane toad.

What do they look like?

Fire ants look very much like ordinary house or garden ants.

 Fire ants:

• Are small
• Are coppery-brown in colour on the head and body, with a darker abdomen
• Come in a variety of sizes within one nest, ranging from 2mm to 6 mm. This is a distinguishing feature of fire ants
• Have nests with no obvious entry or exit holes on top of them
• Can be distinguished by their aggressive behaviour, particularly near the nest

Their nests can appear as dome-shaped mounds, up to 40cm high, or can be found next to, or underneath other objects found on the ground, such as timber, logs, rocks, pavers, bricks etc. Mounds will not always be evident, but are usually found in open areas such as lawns, pastures, along roadsides and unused cropland. Mounds are rarely found in frequently cultivated areas. This species could easily be confused with the common coastal brown ant and as well as some local native ants.

More pictures of fire ants and their nests.

What if I get stung by a fire ant?

Fire ants inflict a fiery sting, which causes a small blister or pustule to form at the site of each sting after several hours. The blisters become itchy while healing and are prone to infection if broken. 

If you are stung by a fire ant:

• Apply a cold compress to relieve the swelling and pain.
• Gently wash the affected area with soap and water and leave the blister intact.
• People who are allergic to insect stings should seek medical attention immediately. On rare occasions, fire ant stings can cause severe acute allergic reaction (anaphylaxis)

What if I think I have fire ants?

Firstly, avoid contact with the ants.

Secondly, report them to DPI&F by contacting the DPI&F Call Centre on  13 25 23 or fill out the web form. Fire ants pose such a serious threat to our economy, environment and lifestyle that they they have been declared a notifiable pest under the Plant Protection Act 1989. This means that landholders who think or know they have fire ants on their property are legally obliged to inform the DPI&F of the infestation. Withholding this information could result in the landholder being fined.

Once you contact DPI&F, an information officer will ask you a series of questions to determine if you have fire ants or common ants. Be aware the DPI&F is unable to send field teams to investigate every report; so your answers to the questions will determine if an immediate field visit to your property for sampling is required.

If you find any nest, DO NOT TOUCH IT. Try to identify if it is a fire ant nest, which may appear as a closed, dome-shaped mound (that is, no opening) up to 40 cm high. In contrast, many native ants build a smaller nest with one or more obvious openings. However, in some soil types, fire ants may not form obvious mounds, particularly in the early months of nest development, or if there is other debris where they can build a nest beneath. 

You could be asked to send an ant sample to the DPI&F for identification, particularly if you are in a remote location.

If you need to take a sample, kill some of the larger ants (the workers) away from the nest by spraying them with a household knockdown insect spray. Use a disposable plastic spoon or something similar to scoop the dead ants into a sturdy plastic container and seal.  Do not add any liquid.

Place the container in a tough envelope suitable for posting, and include your name, address, telephone number and details (eg. a Mudmap) of where the ants were found with the sample.

Photo courtesy of Texas A&M University