Everyone knows these little insects, which live in well-organized societies. Ants may seem inoffensive to us and may be of little concern until these tireless workers start setting up too many worksites on our property. Whether carpenter ants or field ants, they can make life a little less pleasant.

Carpenter ants
Carpenter ants are generally black. They are the biggest ants we see and are up to 8 mm (? inch) long. Also called the black carpenter ant, this species normally lives in large colonies in damp or decomposing wood outside or – unfortunately – inside your house.

Outdoors, ants build their nests in tree stumps, piles of firewood or rotting fence or deck structures. Inside the house, they are attracted by wooden parts such as beams, joists and structural lumber. A squad of carpenter ants can easily cause serious damage to a house’s structure.

The presence of a nest can be recognized by the repeated appearance of small mounds of soft sawdust dug out for anthill burrows. A large colony consists of a main nest, which may be located up to 90 metres (300 feet) from the house, and up to 10 satellite nests sheltering more than 10,000 ants altogether.

Home infestations generally result from the formation of a satellite nest, without a queen, caused by overpopulation of the colony or a major disturbance such as a tree being cut down, a window being replaced or a deck being repaired.
Preventive measures
Several preventive measures can keep ants far from your house.


  • Eliminating any damp or rotten wood around the house
  • Keeping firewood away from the house
  • Cutting tree branches that touch the house, and checking cables (such as electrical cables) or clotheslines that can serve as highways for ants
  • Installing mosquito screens on every opening to the outside of the house
  • Sealing all cracks and crevasses


  • Storing food in sealed containers
  • Washing floors and kitchen counters frequently
  • Using an outdoor bin for garbage

Sometimes, the problem of carpenter ants requires extermination, and this involves destroying the main nest. Although a pest management specialist may often have to be called in, you can attempt to attack the anthill yourself.

Outdoor nests:

  • Repeated flooding of the nest with boiling or soapy water
  • Sprinkling of red pepper, eggshell, bone powder, wood ash or diatomaceous earth, a low-impact powdered pesticide
  • As a last resort, spreading an approved insecticide

Indoor nests:

  • Use of borax-based liquid or powdered bait
  • Spreading of homemade bait near the nest and other places where ants are found, consisting of equal amounts of icing sugar and borax powder. But be careful: borax is toxic for children and pets.

Field ants or pavement ants
Field ants or pavement ants are brown or black and small in size. They are constantly looking for food and proliferate in sandy areas, generally nesting outdoors near house foundations, in their cracks or in those of paving stones or asphalt-covered areas. Small sand craters formed by the digging of burrows often indicate their presence.

Preventive measures
A few minor measures can keep field ants from taking over your home.


  • Sealing of cracks in foundations and exterior cladding, including door and window contours.


  • Daily cleaning of food preparation and consumption areas
  • Regular transfer of table wastes to outdoor bins
  • Storage of non-refrigerated food in hermetically sealed containers

Traps or baits sold at hardware stores and placed in the most ant-prone areas are an effective means of controlling field ants. They can also be dislodged by pouring boiling or soapy water onto their nest or spreading red pepper, eggshell, bone or talcum powder, or diatomaceous earth, a low-impact powdered pesticide.

Please note that use of approved pesticides should be regarded as a last resort. It is vital to read the manufacturer’s instructions carefully and follow them to the letter. Depending on the level of infestation, calling in a pest management specialist may be necessary.