Ant (Argentine ant) Linepithema humile
Species: L. humile
Binomial name: Linepithema humile
Synonym: Iridomyrmex humilis
Common name: Argentine ant
The Argentine ant, Linepithema humile is ranked among the world’s 100 worst invasive species. It is an ant native to northern Argentina, Uruguay, Paraguay, Bolivia and southern Brazil. It is an invasive species that has been inadvertently introduced by humans to many places, including South Africa, New Zealand, Japan, Easter Island, Australia, Europe, Hawaii, United States and many oceanic islands.
The Argentine ant is ranked among the world’s 100 worst animal invaders. The Argentine ant was first discovered in New Zealand at Mt Smart Stadium (Auckland) during opening-ceremony rehearsals for the 1990 Commonwealth Games and through genetic analysis, it is thought they probably came from Australia. This species has a strong tendency to move and associate with humans and is now a problem in an increasing number of towns and cities throughout New Zealand. Argentine ants will hitch rides in freight, potted plants, rubbish, vehicles, camping gear and other such goods. They have now spread to numerous urban locations throughout the North Island and several in the South Island.
These ants are becoming a big problem in New Zealand for many reasons. There are now trade restrictions applied by several countries as a result of contamination of our exports. They are a pest in the poultry industry through stress on chickens and the killing of newly hatched chicks. They also rob beehives, affecting honey production. For full details of the impact of Argentine ants visit Landcare Research’s website at http://argentineants.landcareresearch.co.nz/index.asp
Argentine ant workers are all the same size (2–3 mm long) and are a uniform light brown colour (compared with the common black species found foraging in urban areas in New Zealand). They are often seen foraging along defined continuous trails (not erratic ‘crazy’ behaviour of running about in circles). They also climb trees and plants. The ants can't sting but some people react to their bite.
You can find advice on control at http://www.biosecurity.govt.nz/pests/argentine-ant/control