FAQs related to Argentine Ant

Where will I find Argentine ant nests?

Argentine ants nest mainly in soil, retaining walls, and rock-gardens, under paths or cobblestones or at the base of plants in the warmer months. Wheelie bins and re-cycling containers, planter pots, cars and trucks also provide great nesting sites.

Some of the largest colonies have been found under the fake grass of tennis courts and around swimming pools.

Argentine ants are most active in dry, warm weather, but the onset of wet weather and cooler temperatures drives them into buildings. 

Over-wintering nests can contain hundreds of thousands of ants, and can usually be found inside the north or east facing warmer walls and in ceiling cavities.

The small satellite colonies established during the summer months can come together into huge colonies during the winter months, only to expand again into dispersed nests when the conditions become favourable.

How do people spread Argentine ants?

Anything transported from point A to point B can potentially harbour Argentine ant nests.

Materials that are most at risk of harbouring a nest include rubbish, and garden or nursery products like potted plants, garden mulch, bark chips, and compost.

However, these ants also readily establish nests in cars, caravans, or even aircraft. And in this way can spread themselves across town, or around the country with ease.

Argentine ant infestations are frequently not detected until they have reached the stage of becoming a human nuisance. This may take two years or more. By the time they are detected, the ants are probably well established and may even have spawned sub-colonies that have hitched a lift elsewhere.

How do Argentine ants invade an area?

Argentine ants invade and colonise an area in two ways: budding and jump dispersal.

Budding

Unlike many other ants, Argentine ant queens do not go on nuptial flights, and so form new nests within ant-walking distance of the old nest. After mating, a young queen will simply walk away with some workers, and establish a new nest nearby. Left to themselves, colonies would increase by little more than 200 meters/year.

Jump dispersal

However, young queens will readily ‘bud off’ with a few workers and establish their nests in nearby vehicles, planter pots or wheelie bins. This done, they could end up anywhere.

This ability to ‘hitch’ a lift with humans makes the Argentine ant so challenging to control. And as these ants produce around ten times more queens than other species, the challenge is magnified.

Human-mediated dispersal within suburbs across a city, and between neighbouring towns is essentially creating a large number of small ant populations throughout New Zealand, and these are likely to act as centres for further expansion.

Why are Argentine ants so invasive?

The Argentine ant has a wide dietary range and produces large numbers of aggressive and industrious workers.

They are one of a few ants species worldwide that have been identified as capable of invading native ecosystems and displacing native species, and because of this are listed as one of 100 of the world's worst invasive species by the Global Invasive Species Group, IUCN  (offsite link to www.issg.org)

Argentine ants are omnivorous, with neighbouring colonies being genetically related. The relative lack of in-fighting between colonies makes the species highly competitive in the ant world.

When a colony has fully infiltrated an area, resulting in its complete dominance over other arthropod species, it has achieved ‘Super Colony’ status. The lack of other ant species and insects in the surrounding area is a clear indicator of this.

Super Colonies allow Argentine ants to form extensive, interconnected networks, not only through the suburbs of a town but even across vast distances.

In Mediterranean Europe, where Argentine ants have been established for many years, recent studies indicate the existence of a single, vast colony, stretching almost six thousand kilometres from Italy, through France, Spain and around the corner to Portugal.

Are these Argentine ants in my region yet?

Argentine ants were first detected as an established population in Auckland in1990. They have since spread quickly and are now present in many North Island cities and in two South Island locations.

http://www.landcareresearch.co.nz/research/biosecurity/stowaways/Ants/AAdistribution.asp (offsite link to www.landcareresearch.co.nz)

Argentine ants are often found closely associated with humans and human activities - e.g., in houses, gardens, plant nurseries and industrial areas. A recent study [WARD, ET AL .PDF] found human-mediated dispersal is primarily responsible for the spread of Argentine ants in New Zealand.

These ants hitch a ride in vehicles (including aircraft) and on transported materials of all kinds. They have the potential to spread throughout much of the North Island and northern South Island, as well as some South Island cities.

http://www.landcareresearch.co.nz/research/biosecurity/stowaways/Ants/AAfuturedistribution.asp (offsite link to www.landcareresearch.co.nz)