For the first time since we've lived in our house, we have ants. It also coincides nicely with having a 2-year old who leaves a trail of crumbs!
Last night I thoroughly vacuumed the living room, pulling all the furniture from the walls. Then I mopped, using vinegar in my water since ants supposedly don't like to walk on vinegar residue.
A half hour later the living room had ants crawling all over the floor. And they were carrying food. Where did they get it??? It reminds me of when my daughter was 9 months and I'd sweep, swiffer, mop on my hands and knees and she'd still find all sorts of things to stuff in her mouth!
We haven't found a point of entry, and there isn't a trail. I've read all kinds of things online that are natural ways to eliminate ants, but it's helpful to know where they are getting in or find a trail. Maybe next I'll shake pepper all over the place. ;)