Argentine Ant
Linepithema humile
Argentine ant
This species is in New Zealand
Contact your regional council for advice
Fact Sheet 
(80 KB)
General Information
Argentine ants are listed by the World Conservation Union as one of the world’s 100 worst invasive species. The ants eat a very wide range of foods and invade native ecosystems and displace native species. They produce multiple queens and can form huge super-colonies that extend for thousands of kilometres.
Argentine ants were first found in 1990 in Auckland, where they were well established. Since then they have spread quickly and are now found in many North Island towns and cities and in two cities in the South Island. For a map of their distribution click here http://www.landcareresearch.co.nz/research/biosecurity/stowaways/Ants/AAdistribution.asp 
The ants spread quite slowly naturally, but are great hitch-hikers. They establish nests in anything from potted plants and garden mulch to rubbish and recycling bins to cars and aircraft. When their homes are moved to a new location, the ants get to ride along too. Often the ants are not noticed until they become a nuisance, by which time they have been there for several years and have already spread into the surrounding areas.
Argentine ant workers are small (2 – 3mm long), and a uniform honey-brown colour but can look brown/grey when foraging in urban areas. They are a similar size and colour to some of our native ants, but unlike native ants which only live outdoors, Argentine ants can be found both inside and outside of buildings. Most common household ants in New Zealand are black.
Argentine ants form distinctive trails that may be five or more ants wide, and they will often immediately walk straight over objects that are placed across their trails. Most other ants in this situation become confused for a while if objects are placed across their trails.
Argentine ants look similar to another pest species – Darwin’s ant, but can be told apart from these by the squash and sniff test. When squashed between the fingers Darwin’s ants have a distinctive formic acid smell, Argentine ants do not. Women are often better at picking up this smell than men. Because Argentine ants can be difficult to identify, using the services of a pest control professional is advised.
Argentine ants eat a wide range of foods including nectar, insects, seeds, carrion, and honeydew secreted by aphids and scale insects. Workers have a mostly sugar based diet, while larvae and queens feed mostly on protein.
Although Argentine ants don’t sting, they can bite, causing a reaction in some people. In urban areas they invade homes, gardens, commercial and industrial buildings. Residents in affected areas report a notable absence of most common garden insects following the establishment of the ants. They also notice a rise in the number of aphids and scale insects, as the ants actively farm these, protecting them from predators and even moving them to safety.
Argentine ants have been reported to attack nesting birds and kill nestlings and have the potential to spread into sensitive ecosystems such as coastal conservation areas. They out- compete native ants and other invertebrates for food, as well as preying on their eggs, larvae and adults. They also compete for nectar affecting pollination.
Argentine ants are not susceptible to standard ant control products and use of these products may make the problem worse. A recently developed bait, XstinguishTM is available through professional pest control operators.
Biosecurity New Zealand is working with other government agencies, regional and local councils, research agencies and the private sector to coordinate control efforts.
Management
With many agencies contributing to the control of Argentine ants, there is a recognised need for national coordination of Argentine ant control efforts. Biosecurity New Zealand is working with DOC, regional authorities and other pest management organisations to actively coordinate Argentine ant control as part of a pilot programme.
Included in this programme is improving access to information on Argentine ant control and technical advice, leading a nationally coordinated process to prepare a national plan for Argentine ants, and developing public awareness material.
Useful Resources:
Page last updated: 24 October 2008