Killing ants can be much easier, safer and cheaper than most people realise. The only "chemicals" you will use are dish detergent and Borax, or boric acid. The dish-detergent mixture offers the advantage of being a quick killing agent, while the Borax works as a long-term residual killer. Ants consider this powder to be food, and foragers will feed it to the other members of the colony, including the queen. When the queen dies, so does the rest of the clan.
All the items that you need to effectively fight ants are either already lying around the house, or readily available at any department, discount, grocery or hardware store. The best part is that you can do this without placing your kids or your pets at risk by exposing them to dangerous pesticides.
Fill an empty plastic spray bottle with warm water and add a healthy squirt of Dawn dish soap to it. Then shake it to mix it well. This is a guaranteed quick kill for ants that works upon contact with the insects. Any time you see ants, spray and kill them with this solution, which will keep indefinitely.
Use a screwdriver to remove one switch plate from each wall in every room of the house. In rooms where you've noticed a high level of ant activity, or where you've seen ant trails, remove all the plates.
Use a plastic spoon to scoop up about 1/2 tsp of Borax or boric acid, and deposit the powder inside the metal casing that houses the switch or plug unit. Ants will often travel through the electrical sockets, and most insects will use them to access the rest of the house if they have built nests within your walls. They will scurry through the powdered Borax on their trips to and from the nest multiple times daily, feeding it to their cohorts. Plan to repeat this step once every 3 to 6 months to determine if the Borax needs to be replenished.
Make bait traps and disguise them as feeding stations by filling some plastic bottle caps about halfway with Borax. Place them anywhere you've noticed any ant activity whatsoever. Behind and under appliances, under all sinks, near vents leading outdoors, inside cabinets containing sweets or greases, near kitchen garbage cans, and near doorways leading outside are all excellent locations for these little bait traps. Place some anywhere in the home where moisture is present, because the ants will tend to frequent these areas. Concentrate on the kitchen, bathroom(s) and laundry room.
If you've seen any active mounds, make your own environmentally friendly ant killer for outside the home. Combine about 1/4 cup of sugar with an equal amount of honey in a mason jar. Heat the mixture in the microwave or in a pan of water on the stove just long enough to melt the sugar, then stir to mix thoroughly. Gradually sprinkle in 1/4 cup of Borax by the spoonful, blending very well after each addition.
Drizzle 1 tbsp or so of the honey mixture onto active ant mounds. The sweet bait will quickly attract the ants, and the mound's queen and colony will soon all be killed by the Borax. Cover the jar of bait tightly and store it for up to 2 weeks at room temperature in anywhere that's convenient for you.
Although it's tempting, don't squash, spray or otherwise hinder ants that you see walking through or trailing to and from the Borax. These little guys are now your very own hired assassins, doing your dirty work for you by carrying the powder back to the nest to feed and kill all the other ants. Let your employees do their jobs.
Immediately replace any Borax that becomes wet, as it will be neutralised by the water and won't work anymore.