Caulking! I haven't tried it, but have read a number of times that cornmeal poured into an ant hole will kill ants. That is assuming you know where the ant holes are!

Ants don't like spearmint or cinnamon. I tried painting spearmint oil near where they came in years ago. They defintiely don't like the stuff, but one has to keep reapplying as it evaporates and loses scent. I also used cinnamon powder, but that requires some clean up in the long run.

Because it was the only poison I had, I eventually poured flea powder into the small hole at the base of a door jamb, where they entered. I used a skewer to tamp the flea powder in good. I never had another ant come in. The flea powder sealed the hole like caulk, and probably killed quite a few ants, too.

Lorna

In order of toxicity, I've heard to use:
Black Pepper
Boric acid powder (frequently sold as 'Roach powder')
Sevin dust.

If they are sweet eating ants you can use Terro. This works well for me although it's not non-toxic. You can put the Terro where nothing else can get to it and use one drop on a little card that comes with it. The ants feast and die.
Diamotaceous Earth is non-toxic, all natural and does not hurt living things other than tiny insects that drag through it. I find this more effective than anything else.

GGG

When we had an ant invasion in the kitchen, I sprayed vinegar along their trail and point of entry. They HATE vinegar!

Marilyn

Thanks for your input. Unfortunately i don't know their exact point of entry - I'm thinking maybe the window. I tried cinnamon the last couple of days, but I may not have had it in the right place as they were in again this morning. It's hard to get a handle on this as my college age son is quite the 'slob'(gosh, does that ever go away?!) and so he makes something on the counter and doesn't clean up after himself. Can't imagine why the ants are also in his room... In any case it's nice to have other options to try so next it is vinegar and I think I have Diamotaceous Earth from when I was battling earwigs outside. Thanks! wig

I second the use of Terro. We were invaded last summer because of all the rains here. I thought I'd never get rid of them. It took two rounds to clear them out, but they are GONE!

I mix icing sugar and baking soda in equal parts, and put it where I see them. The theory is, ants cannot burp or fart, so they explode - no kidding. I've used this method, as have a couple of friends with good results. It comes from a local renovator who has a radio show. ;-p

Nancy.