Once you know you have an ant problem the next step is remediation. First, you need to find the nest. You can often track ants back to their colony if you watch for them at night (particularly in spring). If the ant goes outside, you can breath a sigh of relief as you won't have to tear up walls. However, still locate the colony and clean it out before they try to set up a satellite nest inside the home. The key difference between the main colony and a satellite colony is that the latter will be dry. When you find the nest you can then treat it with boric acid or another insecticide of your choosing. Some people simply vacuum out the ants (but you need to do this several times to be sure they're gone. If you cannot locate the nest, or find that your remedial efforts fail, get professional assistance. Ants in your walls can do hundreds and sometimes thousands of dollars worth of damage that only gets worse the longer you wait.