There are two basic types of ant infestations: a one-time occurrence sparked by the presence of residual food, dirty dishes in the sink, a bowl of pet food and so on. In these isolated instances, spraying the trail(s) of ants with a common household ant killer will generally kill off the insects and eradicate the problem.

However, if the ant infestation is chronic and not linked to the leaving out of food or sweet liquids, the logical first step is to properly identify the species of ant in question with a magnifying glass. Odorous house ants, pavement, and pharaoh ants are the three most common types of species responsible for North American home infestations, with each one requiring slightly different extermination techniques.

Preventative Measures 

Chronic ant infestations are the most difficult kind to deal with, as the root cause may be water within the walls or some hard-to-detect factor. Before calling in a professional pest control company, it is worth considering some basic preventative measures to attempt to alleviate the problem. These include sealing all openings in and around the affected rooms with caulking or other sealant. Homeowners may also want to remove any non-landscaped weeds and shrubbery that abut the building's foundation.

The Weather Culprit

Sometimes, the actions of human occupants and the physical state of a residence or business have little to do with the root cause of an ant infestation. The culprit may be something as simple as the weather. A 1998-1999 study of California households found that Argentine ants invaded homes to seek shelter from bad weather, developed immunity to common household ant killers, and chose to exit the premises of their own volition.  Part of the difficulty in dealing with weather savvy Argentine ants is that their colonies feature several queens, whereas most pesticides are designed to kill colonies of ants that have a single matriarch.