Ants can be a nuisance in any home. A piece of candy left on a table will soon have a trail of ants leading to it. Although ants discard wood debris and sawdust as they clean their nests, they do not damage sound timber. Any damage to wood is almost certainly due to termites not ants.
In parts of Australia, ants have become more than a nuisance. After being discovered in Cairns in 2001, the Yellow Crazy ant has spread rapidly northwards, causing mayhem where ever it appears. In Edmonton, one resident says he has been awoken three times at night by acid from the ants hurting his eyes. In some areas, residents have given up tending their gardens as they themselves get covered in the ants.
These same ants have adversely affected the Robber crab population in the Christmas Islands and as a consequence altered the type of plants that grow in that area. There is a fear that a similar effect could soon be seen in the Queensland wildlife. Agriculture in the region is being damaged to the tune of millions of dollars each year, an amount which is expected to grow dramatically unless the ants can be controlled. One report suggested that the cost could eventually be as high as A$3 billion.
The sting of the Jack Jumper ant (Myrmecia pilosula) can be fatal to sensitive people and an anti-venom is now available. Four deaths due to anaphylaxis caused by Jack Jumper ant stings were reported from Tasmania between 1980 and 2000. It is classed as one of the most dangerous ants in the world.
Although there are over 1,300 known species of ant in Australia, only a few are pests. Pest species include the following:
- Argentine ants (Linepithema humile) - a small species between 1.5 and 3mm long, light brown in color.
- Coastal Brown ants (Pheidole megacephala) – light brown in color, between 1.5 to 2.5mm long.
- Pharoah ants (Monomorium pharaonis) – variable in color from yellowish brown to darker brown. 1.5 to 2mm long.
- Odorous ants (Tapinoma sessile) – another small species between 2 and 3mm, which like its name suggests gives off a rancid smell if crushed.
- Carpenter ants (Camponotus species) – a larger species from 7 to 12mm in length and variable in color.
- Meat ants (Iridomyrmex purpureus) – an even larger red and black species up to 15mm long.
- Bull Dog ants (Myrmecia species) – an aggressive ant which can be 20mm long, red or black in color and has long jaws. These are primarily garden pests that can sting repeatedly.
- Jack Jumper ants (Myrmecia pilosula) – a close relative of the Bull Dog ant, these 14mm long ants are black with orange jaws and legs. They are also known as Skipper ants or Hopper ants. They are a dangerous ant, responsible for deaths every few years due to anaphylactic shock caused by their sting.
- Fire ants (Solenopsis species) – a small species, about 6mm long, that will normally build a mound in the garden but may invade a home. If disturbed they sting aggressively.
- Yellow Crazy ants (Anoplolepis gracilipes) – only about 5mm long but listed in the top 100 worst invasive species of any plant or animal in the world. These ants don’t sting, but they may spray formic acid.
The first step in controlling ants is to find their nest, which is not always easy. Spraying individuals or even lines of ants will not harm the colony, where thousands of others are available to take their place.
It is important to identify the species to be eradicated. Single queen colonies are easier to destroy than those with more than one queen. Incomplete extermination of a colony with more than one queen might cause the survivors to abandon the original site and split into several colonies.
In the garden or yard, colonies may build small mounds or nest next to or under boulders. Outdoors, their nests are invariably underground, so follow the lines of ants. Even if the entrance to the nest is small, soldier ants can normally be seen on guard outside. If a nest is found in the soil, it can be treated with various types of insecticide, such as a Pyrethoid or Bifenthrin liquid. The insecticides are pumped into the nest area, often under pressure.
Indoors, ants may build their nest in walls, under foundations or between bricks. Baits are normally used against an indoor ant invasion, placed in containers to avoid risk to children and pets. Like termites, ants are trophallaxic so the workers will take the insecticide bait back to the nest and share it among the other ants, leading to the death of the colony.
The bait will normally kill the ants within about three days. It should be placed near to or on the ant runs.