Ants are social insects, living in colonies. There are hundreds of native species, some associated with timber, but none of the ant species present in Australia damages timber which is in good condition. In their natural environment they are important as predators and scavengers and contribute to the recycling of nutrients to the soil. In domestic and industrial situations they can be a problem.
Most ants do not cause problems, but a few are pests in the garden and in buildings. They will infest decaying timber in retaining walls, fences and in buildings, and their activity is often mistaken for that of wood-eating species.
Workers foraging in buildings generally come from external nests. A few species nest in wall cavities, ceiling spaces and behind skirting boards. Internal nests can be very difficult to eradicate.
Small piles of gritty material often appear by door and window frames and skirting boards, and reappear each time they are cleaned up. Similar material falls from timber ceilings and collects on furniture and floor coverings. The debris is produced by ants and can include faecal pellets, wood fragments, dust and fibres and the remains of insects and spiders, as shown by microscopic examination.
Ants keep their trails and nest clean by collecting and dumping waste and litter. Rubbish is often dumped from the same outlet, hence the regular reappearance of debris. Movement and friction in wall frames and ceiling timbers can produce small wood fragments. New houses usually have carpentry dust in the wall cavities and roof space. Ants discard the wood fragments and other debris, giving the impression that timber is being damaged. However, as previously stated, in Australia ants do not damage sound timber and the wood fragments in debris are associated with cleaning activities.
Hygiene is important. Food preparation and eating areas should be kept free of food particles and waste, and susceptible foods stored in airtight containers or in the refrigerator. Where pets are fed regularly in one place, leftovers should be cleaned up immediately. Decaying timber, which would provide nesting sites, should be removed.
Several insecticides in liquid, powder or granular form are available for use against ground-nesting species. The most effective method is to find the nest and destroy it. Nest entrances can often be located by following ants carrying food, and small pieces of sweet food or cooked meat may be used as bait. An insecticide is then introduced. Trails can be sprayed, but this is not effective because surviving ants will mark new trails away from the treated areas.