A leading insect expert has called a recent outbreak of red ants in Sydney's Port Botany "so serious" warning we should be more afraid of the creepy crawlies than sharks.

Invasive Species Council chief executive Andrew Cox told ninemsn an infestation of the insects in Texas has already claimed several lives, including that of a 13-year-old boy.

"They can kill people," Mr Cox said. "Young people and the elderly generally have got less ability to respond to stress and can go into shock after a bite."

In a statement to ninemsn from the NSW Department of Primary Industries the ants are described as being a "reddish-brown in colour with a darker abdomen".

"Fire ant nests often look like disturbed soil or a small mound of soil with no visible entry holes. If disturbed the ants may become aggressive and swarm," the statement reads.

DNA tests carried out on the ants confirmed they originated in Argentina. It is believed they arrived in Sydney on a cargo ship.

Mr Cox said because of the ant's size – they measure between 2mm-6mm – they can be nearly impossible to see.

"People assume because they are so aggressive they would be quite meaty, but you can easily fit a bundle of them on a 5c coin," he said.

Close-up photograph of a red ant. (AAP)

The DPI's director of invasive plants and animals, Dr Andrew Sanger, said that at this stage the outbreak is contained to one colony but warns the ants may "be in the suburbs already".

According to Mr Cox the ants "like open areas" such as "parks, football fields and people's backyards".

If bitten, he recommends dousing the bite in "cold water" and to move away quickly.

"They are very aggressive. Any disturbance and the ants will swarm and attack the very thing that is nearby," Mr Cox said.