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Ants are social insects which live in nests. The nests vary in size depending on their age and the species of ant. They are generally found in the ground, in wood or under rocks, although ants can also nest in walls, fireplaces, under paths and in buildings. They are most active from October to March. Ants are a very successful insect group with over 1200 species occurring in Australia. All species can be beneficial to the environment. Some eat insect pests such as termites, their nests improve the soil, they quickly recycle nutrients back into the soil and they are food for a wide range of native birds, reptiles and other small animals. Although ants are environmentally important, some can also be pests to people. Their nests and the ants themselves may be considered unsightly and they may kill or damage seeds or seedlings. Some ants bite or sting, eg. the bull ant. Ants can also cause damage to houseplants, nursery plants and crops by the cultivation of sap sucking insects such as scale and aphids. Ants use the honeydew produced by these pests as a food source and in turn protect the sucking insect from attack by predators.
The most common species of ant in Canberra are:
- The Black House Ant ( Iridomyrmex glaber) and White Footed House Ant ( Technomyrmex albipes) are small black ants 2.5-3mm long. They nest in rockeries, near or under paths, in wall cavities and in potted plants. They eat a variety of foods and are attracted to sweet substances. They give an annoying bite but do not sting.
- Meat Ants ( Iridomyrex purpureus) are 12-14mm long and are red/purple and black. They like sunny areas and often build large gravelly mounds. They feed mainly on animal material, and honeydew. They can bite but do not sting and rarely enter houses.
- Sugar or Carpenter Ants ( Camponotus species) are 5-15mm long, they have orange/brown bodies, black abdomens with an orange/brown band and black heads. They nest in decayed moist wood or sometimes in the soil. They feed on dead and live insects, honeydew, household waste and are attracted by sweet food. These ants do not sting and rarely enter houses.
- Bulldog or Bull Ants ( Myrmecia species) have red bodies and black abdomens. They are about 20mm long. These ants can cause a painful sting. They rarely enter houses and are usually found in the garden or bushland areas.
- Argentine Ants ( Iridomyrmex humilis) are about 3mm long and are light to dark brown in colour. They do not have the formic acid smell ants usually have and they are very active in their movements.
Sanitationis important in preventing infestations by ants. Inside the house, pet food bowls, dirty dishes, food crumbs on the floor, benches or tables and sap sucking insects on indoor plants can all attract ants. Outside the house, unemptied rubbish bins, food and old drink cans also encourage ants. Keeping these areas clean and controlling sap sucking insects indoors will greatly reduce the chance of ants becoming a problem around the house. Placing pet food bowls in a tray of water may lessen the problem.
Chemical control may be warranted if a persistent infestation of ants causes a problem/nuisance. Your local garden centre can recommend appropriate controls and insecticides. There are several options available.
- Using a commercially available or homemade ant bait may be all that is required.
- If the ants are more persistent, then the ant nest may need to be chemically treated (use Baygon* Dust). This treatment can be carried out by the householder if desired but seek professional advice first.
- The application of chemical barriers between the nest and food source can be used where it is impossible to treat the nest.
- Application of insecticides to the surfaces where the ants are travelling can also be used but this does not provide very effective control.
* Baygon is a registered trade name.
Warning on using garden chemicals: Most garden chemicals are poisonous so avoid using them. Where possible use physical control or non-toxic deterrents. If you must use a poisonous chemical, take these precautions:
- keep chemicals out of the reach of children
- read labels carefully and follow directions exactly
- wear protective clothing - at least long trousers, long sleeved shirt, waterproof boots and gloves and a washable hat
- spray on a still day to avoid spray drift
- do not use insecticides when plants are in flower because most are poisonous to birds and bees.
Identify your problem carefully. Chemicals may not be the solution.