I was just surfing the website and saw your post and had to reply... I hate killing ant colonies too especially since I live in Arizona where horned toads primarily eat them. I had problems with them defoliating my trees so I did some research and it was hard to find a solution without killing the colony, but what worked for me was Green light insect repellent granuales (I buy them at lowes
http://www.lowes.com/pd_250140-38888-80512_0__?productId=3028303). I like to wait until night, or when they are less active, and make a perimeter around the trees or in your case house. Then I swept out the trails. That helped until a heavy rain washed away the granuales and they found the trees again. The granuales are made out of cedar dust (waste from the furniture business) and it disrupts the ant's sense of smell so she can't find her way back home to tell the other ants where to go. This way the colony lives on and you don't have ants in the house. It would help keep other insects out of your house too:)
Alice
