This is easy, get yourself some Andro or other like product ant killer. Get the bait kind that targets ants and your problem will be gone.

Thanks for the quick reply.
I should have included my wish to use chemicals only as a last resort, since pesticides don't fit well into my style of gardening. Amdro seems to be quite the macho bit of overkill, even if it's effortless.

I suppose I need to find out first if these ants are harmful. If these are Monomorium Minimum, the "Little Black Ant" then eradicating them might not be necessary.

There must be some environmentally balanced options. Would overseeding with clover work better than grass (in this type of light??) to hide the sandy bare spots?
I'm not a grass-fanatic, most of my gardening time is spent on perennials, but I don't want bare spots in the lawn, either.

Amdro is an ant bait product...there isn't anything "macho" or "overkill" about it. You have an ant problem....a really big ant problem, from what you said in your original post. Anything you plant in that area, if you don't get rid of the ants first, will probably struggle to thrive or even survive. The tunneling activity creates air pockets around the roots of plants and causes them to dry out, plus they can't make proper contact with the soil.
If you allow the colony to remain as is, you will probably always have bare patches in that area.
The Amdro won't target other insects in your garden, just the ants. And if the bed is as large as you say it is (HOLY FREAKIN' COW! 5X4!!!!!!! ), the type of ants living in it becomes a moot point....no ant bed of such gigantic proportions can be a good thing on residential property.

RENEE

I guess I have to qualify my use of the term "macho". I went to the Amdros web site, which seems "macho" to me. Starts off with a contest for a trip to Daytona races, then launches into sales hype packed with "overkill" power words (weapon, protect, fight back, image) aimed squarely at the male weekend warrior.
Most ridiculous is the ad copy for Image : "Who Says Image Isn't Everything?!? When Your image is in Dire Need of Rescue...Think IMAGE Herbicide!" Good lord....

The product is designed to kill Fireants and their other products also seem to be intended for southern regions. Hence my term "overkill". I am in zone 5. We have no fireant problem. So far, except for messing up my grass, these ants haven't proven to be harmful. Amdro perimeter product covers other ants, but doesn't imply that it manages nests.

The MSDS sheet indicates that runoff by this problem is an issue for surface water, which we have in abundance around here. Besides, it is explosive. Yikes. Way too macho for me :)

Try this website: http://bugguide.net/node/view/32771 and see if you can i.d. the ant.You may have to search a bit on this site but you should be able to find out what kind they are. Or bring a dead one to your local extension agent or show it to someone nearby who might be able to i.d. it. The Organic Lawn
forum might be able to help you too. Supposedly, if you mix boric acid with sugar, you can kill ants that way.Diatomaceous Earth is also supposed to kill insects. Google around for organic pest control.I would not recommend the boiling water method on such a large area especially if there are children, pets, plants or bare skin exposed. Hope this helps.

Think IMAGE Herbicide!"

Yeah, it's a bit much. The only one I can think of that's more direct is "Kills bugs. Dead."

What, I'm supposed to kill bugs so they live?

I agree with Renee; 5x4' is frigging huge. What are they eating? If you can control the food source, that would sure help. But unless you do something, they're simply not going to allow you to grow anything there.

I found this but I've never used or bought it and don't know how well it would work.

Maybe even standard ant bait traps during dry weather. You really have to keep dogs and children and critters away or it'll kill them, too. It's a last resort, and one I don't like.

Once controlled and gone (but not before or you're just adding to the problem), restore the soil with organics. Lots and lots of organics. Soybean meal, coffee grounds, corn meal, alfalfa, Milorganite from your big-box store, matters not. The organics will help the soil to retain water. Topsoil, sure. Add that too.

I don't suggest digging it (more than 4" or so anyway) because I doubt you can go deep enough to get anything appreciable done--and the soil is going to settle. Hence the topsoil since the organics will rot in and also settle.

If the colony is that well established I doubt the bait will work as fast as you may want it too anyway. You could try a very strong molasses/sugar water mix in a 2-gal pail and drench the top on the colony. With that size area I'd use several pails and do it in early evening after they have finished foraging so none escape.

Anyway, a stronger drench may be necessary, but you could try the above first.

I had a carpenter ant infestation in my house last spring. I put some confectionate sugar on the ground so they thought they found a new food source. Then I laced the sugar with a little powdered borax. Within days they were gone.
Your colony is far more established, but this would be a non toxic way to go. It's worth a try, borax soap is cheap.

Just google "ants borax" and you should find the sugar/borax mixture ratio, i don't remember exactly what it was, maybe 1 cup sugar/2tabblespoonns borax?

If you want to grow grass on this spot, you are going to have to kill the ants. A colony this large just tears up the ground so much that the grass roots will never take hold properly. If you want to kill the ants organically or chemically is up to you, but they do have to go if you want to garden in the spot.

My recommendation is to go to the grocery store, and buy a box of hominy grits. It's in the aisle next to oatmeal, because there are some southern people who eat this for breakfast.

In dry weather, sprinkle the grits on the anthill. Enough to make a layer one grit deep over the whole hill, but no more, and no less. Each grit will be eaten by an ant, and hauled underground. That grit will expand, from body moisture, in the ant's body, and cause the ant to explode. Probably (I have never looked) the grit substance will then dry out, and contract, until another ant then eats it again, with the same repeated result.

When the grits have been dragged from the top of the anthill, pour some more grits on the hill. Very soon, no more anthill.

Thanks for the tips, everyone.
I'm not sure what grits are or if you can buy that up here. Does it have another name?
What is the molasses/sugarwater ratio? That sounds like something I might want to start with.
I found more results of why NOT to use Borax than those that recommend it, so I'll give that a pass.

Good point about "what are they eating". What are they eating? I ought to spend a while following their trail to check that out. Interesting, though, is that when you look closely at the colony, you don't see dozens of them scurrying around, as you would with the little brown ants. You actually have to look close to find them. Maybe it's just a very old colony?

I ought to take a picture but my neighbors probably already think I'm a little soft in the head for staring at my plants so much. (It's a PLANNING process...)

Hope they are not Carpenter Ants and get to your house. You will think twice about a bait that targets ants only when they carry your home away, or a stinging type that attacks a pet or family member.

Plain old ant hotels. The bait variety that are rated for indoor/outdoor use. Some are safe enough you can even put on your kitchen counter.

Molasses worked here in a hose end sprayer. I don't know why. Maybe the yard became so tasty the ants were driven off by the noises created from all the stampeding herds of other bugs that came running for the feast.

"there are some southern people who eat this for breakfast."

In the south, grits are served with every meal. It's only when you get farther from civilization that they become a breakfast only food (at least that's the way a southern friend explained it).

I'll have to ask one of my Canadian friends if you can get them north of the 49th.

chris_ont - I forgot the exact measurements, but shoot me an email and I'll get you more info.

What are they eating?

You don't have any missing-persons reports in the neighborhood, do you?

I ought to take a picture but my neighbors probably already think I'm a little soft in the head for staring at my plants so much. (It's a PLANNING process...)

Ha! Yeah, me too. Don't worry about it. Around the time your lawn and gardens are the most abundant and beautiful in the neighborhood, they stop wondering and start wandering over.

Chris--I asked a Canadian friend where he gets his grits and he told me that he mostly got them in Philadelphia. He suggested the breakfast section of the supermarket, followed by the baking section. If that doesn't work, he said to try someplace called Bulk Barn.

Wow, you were serious about using grits to kill ants?

That's got to make grits the most MACHO breakfast (or other meal) possible!

If you don't want to kill them - especially with a "macho" product - why not have a neighbor invite them for tea? Maybe they will be so kind as to move of their own free will. If not, maybe put an addition on your house so they can at least have a roof over their heads. (Where's your compassion?) If you are thinking of actually digging them up and finding the queen, why not just move all of them one by one to a wildlife preserve? Give me a break.