- Written by Nadia O’Carroll
Fire ants are native of South America where their numbers are kept in check by pathogens and predators such as insects, armadillos and anteaters. Photid flies prey on fire ants in a particularly gruesome way, they pierce the fire ant’s body and lay eggs, when the larvae hatch they eat the brain of the ant while it is alive, the ant wanders around in a zombie like state for some weeks, until it dies and an adult fly emerges from the ant’s head.
In 1929 fire ants were introduced into Alabama, USA, through soil ballast in ships. They now occupy 300 million acres in southern states, sting 20 million people pa, cause environmental damage, species extinctions, damage crops and electrical equipment, have killed 80 people and countless animals and although eradication is now impossible they cost USA approximately $6.4 billion pa.
There are a number of characteristics that make this species such a dangerous pest.
Fire ants use their jaws to first bite and grip their victim, then they sting repeatedly with a retractable abdominal stinger that injects toxic alkaloid venom. The sting induces a painful burning sensation (hence the name fire ants) and produces a pustule and swelling. If not removed they continue to sting repeatedly in a circular pattern. Fire ants attack their victim’s eyes, mouth and nose, which can blind and suffocate even relatively large animals.
Fire ants are voracious omnivores and consume insects, reptiles, turtles, birds, mammals, seeds, bulbs, fruit, grass and saplings. They will quickly swarm over a victim in huge numbers, when stinging they emit alarm pheromones which makes all of them sting repeatedly in unison.
Fire ants live in large colonies, the queen ant may lay up to 1500 eggs per day. There are two types of colonies, monogyne colonies have one queen, its members are territorial and will defend their colony from foreign fire ants. Polygyne colonies, which have more than one queen, are not hostile to fire ants from other colonies and unfortunately this allows the development of dense super colonies.
Fire ants spread naturally through colonisation and through human activities, mainly transportation of infested plants, landscaping supplies and equipment.
How do you recognise fire ants
They are reddish brown ants, with a variety of sizes (2mm to 6mm) within the same nest, they are very aggressive and will swarm rapidly, their nests are dome shaped mounds of granular soil without visible openings because they enter through underground tunnels.
If you suspect the presence of fire ants do not try to eradicate them yourself, notify Biosecurity Qld on 13 25 23 or refer to Dept of Primary Industry website www.dpi.qld.gov.au.