Living out in the country, we've always lined "trouble" spots around the house with Borax (20 Mule Team, specifically). It has a double effect of keeping all other ground-skimming bugs out of the house as well.

Ants pick it up in their leg hairs, it irritates them, they "clean" it from their legs with their mandibles, ingest it, and it basically cuts them up inside.

The rest was detailed above. I've never seen tell of Borax not being "green" other than through production methods, which I can't control. I know it won't hurt you, I use it in my wash at times, and we use it on the baby's diapers while they're soaking.

I tried the Borax this summer to kill the ants. I'm not sure if the ants are dead but the grass in the area sure is. I guess maybe I put it on too thick. If they are still around in the spring I will have to try something else.

You normally use the borax inside the house...

Borax = powdered boric acid (Sodium tetraborate). It will kill vegetation, because of the pH level, I guess.

Normally, you'd just sprinkle a line of the powder around places where the ants are coming in/frequenting, usually in a tray or box mixed with sugar.

I recently got ants in my car... I parked in the wrong spot at work when it was raining heavy, my car was good shelter... it was an invasion! They were all over in my trunk! I mashed them with the edge of a piece of bamboo flooring I had in my trunk. I crushed line after line of them, and wound up having to spray to get the last of them. Not exactly the best way to go, since I sprayed, and got my carpet all covered in ant residue... I told my wife about it, and she asked why I didn't just use the vacuum...

So, fast forward about a month...

My wife's car get's parked in the wrong spot when it's raining out... you guessed it, the trunk was teaming with ants! I used the vacuum to precisely extract them from the carpeting and follow their lines back to where they had called home. I wasn't able to get them all, but I did get a lot of them! I still kill one or two every time I use her car. I really don't want to spray chemicals in it since it is in so much better shape than mine.

I have never had this problem before...

In response to the boric acid, isn't it a salt? salts will kill the vegetation, and you will have to try to dilute it out before things will grow in it again. I tried the boiling water on a fire ant swarm out front of my house since I needed fairly immediate results with company coming over, and it killed everything in that ~1 square foot area (plants and ants), I was kind of bummed about it, but the grass is already growing back in, and the ants are not a problem. I think if I do it again, I will be more precise with my pouring, and I think I will stir up the pile to open it up, making it more like a crater, hopefully it will amplify the effect of the water, and reduce the plant killing.

The article below has a few more suggestions on how to get rid of not just ants, but a few other pests.

15 Homemade Organic Gardening Sprays and Concoctions That Actually Work : Planet Green

I just thought I'd mention that EVERY hurricane uprooted tree I have ever seen has had an extensive ant nest through out the roots with what appeared to be a normal ant hill at the surface near the trunk. The ants un-compact the soil and cause the roots to have a very hard time holding on to the ground.

A radio station buddy of mine in Biloxi is Anal about killing ants near the tower base, and at the guy wire anchors. It showed after Katrina he was the only station without a damaged/ fallen tower for 20+ miles.

As far as what to kill them with, Borax is as close to organic as I know, but its effectiveness is limited.

Does arsenic work on ants? You could get it in liquid form and mix it with sugar, fi you don't have other humans/animals to worry about.

I found another way today. Apparently ants eat cornflower, but they can't digest it. They'll take it back to the nest and feed it to the queen even. Simple and very green way to go.

Environmentally Safe Way to Kill Ants

It's awesome! I wonder what other insects it works for?

sweet, I'm trying the cornmeal today, my fish food flakes caught my eye yesterday as they were walking out of the automatic feeder.