ARGENTINE ANTS
The Argentine ant, Linepithema humile is one of the world’s most invasive and problematic ant species.
It is native to Argentina and Brazil, but it is now well established in New Zealand – in urban areas, horticultural regions, near ports and on an important conservation islands!
What are they?
Argentine ants are one of the worlds most invasive and problematic ant species. They are very aggressive and bite people, and are one of the major household and garden pests. They reach huge numbers, which means they have a huge appetite and the potential to have a massive impact on the natural environment. Therefore they pose a serious threat to the conservation values of areas such as Urupukapuka Island, Motukawanui Island, Moturua, and many mainland sites.
These threats include:
- eliminating other species of ants
- competing with kiwi for food such as insects and worms
- competing with native birds and lizards for nectar
- displacing and killing native invertebrates
Although ants seem little and insignificant to us, once we look into their world they become important. The way Argentine ants build their homes and the way they communicate are unique. In addition, the social structure of the Argentine ant is different from other ants.
HABITATS
The Argentine ants can usually be found in the top six feet of soil. They can live in moist soil underneath buildings and by sidewalks. Boards can also be used as shelter. Sometimes colonies develop in potted plant soil. Nests can be made of rocks, twigs, dirt, and so forth. Argentine ants relocate their nests often. Food sources and temperature affect where nests are built. Other types of ants live in anthills that look simple on the outside but contain a labyrinth of specialised chambers.
What do they look like?
Argentine ants are small (2-3 mm long) and honey-brown in colour. They are often seen moving in thick trails of up to five ants wide and, unlike most other ants, they climb trees to get to food sources. Often when people start to notice an ant problem around home where there hasn’t been one in the past, it is due to Argentine ants “moving in”.
Argentine ants are in the order Hymenoptera and the family Formicidae. The Argentine ants’ antennae have twelve segments. The thorax joins the abdomen by a thin pedicel, a thin stalk.
There is no smell if one ant is squashed alone, but if many are squashed there is a musty, greasy smell. Workers forage for food and chew it. The food substance is given to the larvae. They digest and regurgitate it for the adults. This must happen because the adults have a very thin esophagus and cannot swallow large particles of food.
Although Argentine ants seem no different from other ants, they are. Argentine ants are social insects. Edward Ruppert and Robert Barnes, in Invertebrate Zoology (Sixth Edition), describe a social organisation as having “individuals functionally interdependent yet morphologically separate.” They stated that no “individual can exist outside of the colony nor can it be a member of any colony, but the one in which it developed.”
Usually ants of the same species, in different colonies, will fight each other. However, Argentine ants cooperate with each other. Argentine ants can be aggressive to other insects. They can exterminate native Ant colonies and kill or drive off paper wasps and bees.
