Habits

Of the thousands of different species of ants in Australia, only a few are considered pests in and around our buildings. Individual size seems to be relevant to pest status. The large bullants, trigger ants, sugar ants, meat ants and even the greenhead ants are of minor consequence if you're not a keen gardener or you haven't been stung. These ants seldom come inside buildings. It's the small black and brown ants (up to about 5mm long) that develop large, hard to find colonies that are of most concern. They can undermine pavers and the root zone of plants, they can damage and short circuit electrical components enough to cause fires, they can transfer viral, fungal and bacterial plant diseases while removing the sweet secretions from aphids, bugs and scale insects. If it can possibly be considered to be food, there is a species of ant that will want to take whatever it is back to their nest. There's a fairly loose generalisation that brown ants prefer protein and black ants prefer carbohydrates and that brown ants are more likely to nest in the building and black ants outside. Just don't count on it. It is also said that a surge in ant numbers and black ants moving their young and nest up into a building is a good indicator of impending rain. Don't count on that either. Although ants have comparatively powerful jaws and they do bite, the pain comes from the hypodermic sting or from venom sprayed from the tip of the abdomen over the area bitten. Large painful welts are almost instantaneous and allergic reactions have caused deaths.

Biology

Winged male and female reproductive usually leave a mature colony to set up their own in a moist and secure crevice. They drop their wings and produce eggs that hatch into larvae and pupae which have to be tended and fed by the "royal" couple. The young become sterile female adults or workers and they soon take over the operation, defence and extension of the nest...and the foraging for food. Later on, some species such as the Coastal Brown and the Singapore ants develop big headed soldier or major ants (also sterile females) which specialise in defending the colony and cracking open grass seeds etc. Argentine and Pharaoh ant colonies have many queens and millions of workers in an enormous conglomeration of interlocking nests.

Adult ants have elbowed antennae and a "waist" of 1-2 segments, a globular abdomen with a sting on the tip. The eggs, larvae and pupa are usually white and immobile. Often these can be seen being carried by workers to a new nesting site.

Management

Colonies of the larger species of meat ant and bullant are easily found and destroyed and readily succumb to urbanisation. Mechanical or pesticidal destruction of nests should be the main aim. It is almost impossible to prevent foraging ants entering a building and although you might make a valiant attempt to reduce available food and liquid, you will not eliminate ants this way. When nests cannot by found, baits and judicial sprays along the trailways and dusts puffed into crevices are the next options.