Ants

Scientists believe ants evolved from wasps in the Cretaceous Period, about 110 million years ago.  The earliest fossil ants have been found in North American amber, which has been dated at 94 million years old.

The ant fauna of Australia is especially large and diverse. World-wide, there are 16 subfamilies, about 300 genera and about 15,000 described species and subspecies of ants.  Thus Australia currently has representatives of two-thirds of the world’s ant subfamilies, one-third of its genera and, as far as we know, about 15% of its species.

After hatching from an egg, ants begin life as larvae.  The differentiation of the female castes (into queen and worker sub-castes) is largely determined by environmental factors such as:

·     The amount and quality of food;

·     Temperature ; and

·     Hormones produced by workers and the queen.

Males usually develop from unfertilised eggs.  Workers generally live one to three years depending on the species and climate.  Queens usually live much longer than the workers, some species having been kept in laboratory nests for up to 29 years.  Males generally live only for a few weeks and die within a day or two of leaving the nest on nuptial flights.  Most ants are general predators or scavengers.  Solid prey, which is most often seen being carried by workers, is intended as food for the larvae.

Adult ants feed exclusively on liquid foods.  They collect these liquids from their prey, while tending hemiptera (true bugs) and other insects; and from plant glands on plants.

Returning foragers pass the liquid food to other adults, especially those that remain in the nest (such as the queen).  Trophallaxis occurs when liquid food that is stored in the forager's crop is regurgitated for nest mates on demand.

Ants are one of the few groups of animals which modify their immediate environment to suit their needs.  They build often elaborate nests in a range of situations, sometimes expending huge amounts of energy in their construction.  Only a handful of animals manufacture such elaborate and complex structures.  While many ants form elaborate nests, those of other species are relatively simple. Many of the species found in rotten wood do little more than remove loose wood fibres to construct simple chambers for workers and brood. Others nest arboreally. Their nests are most frequently found in twigs, branches or trunks of trees.

Ants are social insects which form small to large colonies.  Communication between members of a colony is almost entirely chemical, with some tactile communication. Tactile communication is mainly used as requests for food between adults.

Ants use pheromones to:  Recognise colony members;

Mark trails to food/water sources;

Determine caste; and

Signal attack and defence.

Some ants, such as bulldog or bullants, are troublesome because they give painful stings, while the venom of jack-jumper or jumper ants can cause severe allergic reactions.  Unlike bees that can only sting once, ants can sting multiple times.  Others, such as meat ants and green tree ants, don't sting but bite and then spray formic acid into the wound.  Some ants are nuisance pests when they make mounds, disturb paving or invade buildings.

Some introduced species are both nuisance and environmental pests, including:

·     Argentine ant (Linepithema humile);

·     red imported fire ant (Solenopsis invicta);

·     crazy ant (Anoplolepis gracilipes);

·     electric ant (Wasmannia auropunctatata); and

·     big headed ant or coastal brown ant (Pheidole megacephala).