Got an Ant Problem? Use Aspartame:

For all the dire health problems associated with aspartame -- the worst of them being cancer -- the original 'anything-but-sugar' substitute may have an ideal purpose to exist, not as a food additive, but an ant poison

Already aware of aspartame's origins as a toxic chemical, a health conscious consumer with an ant problem emptied one packet of aspartame in the corner of each of her bathrooms two years ago. The 'sweet' solution worked brilliantly, as she's seen no signs of carpenter ants crawling around for the past year.

Aspartame may be just the thing for getting rid of fire ants (impervious to many poisons) too, although this solution takes a bit more effort. Initially, fire ants ignored their aspartame treat until a light rain moistened it. After the rain, however, the fire ants came back with a vengeance, taking the aspartame back to the mound by the hundreds. Within two days, any evidence of fire ants existed at all, save for an empty mound, vanished.

There are a couple more paragraphs to this post, which you can get to at the link above.

Now I finally know what to do about our ant infestation. Gonna go buy me some "Equal" today...