Ok, I have been dealing with these bastards for a while now, and it is a war. Here is a safe way to kill them off.
1. Go on the offensive, they come in waves so just because you don't see them doesn't mean they won't show up on your doorstep soon. I start looking for them in the spring, March. So put down your traps before you see them.
2. You can make traps with granulated sugar and Borax. Take a coffe can and mix borax (boraxo at your super market, and sugar 50/50. Get some jars, I like baby food jars, but you may not have them. Also small cans will do. fill the jar or can about 20% with the mixture and add water to make a gooey liquid. If you are using jars, make holes in the lid with a nail or all.
Lay the jars or cans on their side so the ants can enter an leave with the liquid. Place the jars in areas around your house where you see the ants and at the 4 corners, preferably under the down spouts. The ants take this mixture back to the nest to feed the others including the queen. This should wipe them out in a few days.
3. Go on the offensive and look for nests in wood and trees around your house. Place the same traps out in these ares.
4. Replace the jars every 4-6 weeks, I usually do this around 3-4 times during the spring and summer season. Don't wait unitl you see them.
Now I am ant free all year long and I don't have to use any pestisides.