I used beneficial nematodes for ant control and hundreds of other types of bugs. Spraying molasses will drive ants to your next door neighbors. It probably works very well since ant mounds are always small and never seem to last long while my neighbors would have huge ant mounds and are there for a long time if done nothing. Do you have any grass at all? What did you do after you had done core aerating? It should be ONE TIME ONLY... core aerating followed by compost then keep up with quarterly feeding with soybean meal to keep the microbes from compost growing and improving the soil over time. In a few years, it should be much improved... as long as you stay away from chemical stuff. If you really want to improve the clay soil, you must practice organic meaning no synthetic chemicals of any kind at all that would ruin soil biology that is responsible for improving soil.

I am having the same problem. The little bastards moved in just a couple weeks after I put in the raised beds. Ugh, it gives me the creeps. I've been using the suggestions in Howard Garrett's book and so far nothing has worked. This is what I've tried: 1. Use a soil drench containing orange oil. This does kill the ants on contact, but it seems to have no residual effect. As in, the ants will mill about inches away from where I poured the orange oil acting not the least bit repelled. The orange oil will harm your plants so I don't want it too close to where things are already planted. It's a good thing to use on mounds, but unless you can manage to get the queen, it just kills some ants and the rest move a few inches away. 2. Spread dry molasses. Again, this is supposed to repel ants and has no effect whatsoever. The ants are very happy to remain in my comfy beds. I've also heard beneficial nemotodes can help, but I haven't been able to find any. I placed an order for a spinosad based bait on Amazon today, as none of the stores in my area carried it. I hope the spinosad works.

I just posted this in another thread but it is relevant here. This is a quote from the Texas A&M website referenced above: "Spinosad (0.5% liquid) - considered all natural or "organic." Has a fire ant mound drench statement on label. Available from Green Light or FertiLome. Green Light product is certified organic by OMRI meaning it is approved for use in organic gardens. Spinosad is a biopesticide produced through commercial culture of a soil-born microbe that produces metabolites toxic to certain insects. These metabolites are harvested and formulated as an insecticide, so the final product contains no living microbes." I have used both brands with great success. Green Light was better but I don't see it for sale any more. By the way, I have tried many other organic remedies and none of them worked great. It does take a little practice to use these but if you apply them when it is above 65F and in the morning with clouds is best. Evening works too but sometimes it needs to be applied more than once. My experience is if it worked they are gone in less than 4 days.

I have killed huge fire ant mounds by using the used coffee grounds that Starbucks gives away for free. After experimenting with these used coffee grounds for 8 years, I have found all kinds of interesting uses for them. Mainly as a direct contact spray, I can take care of all the insects I have problems with, and I have 40,000 plants. I found that the coffee spray will not kill ants, but they ARE repelled by the used coffee grounds. This may take a little practice, but I take the used coffee grounds and mix them with enough water that they turn into mud. I put a thin layer of mud all over the mound, and I found out the trick is to cover another 4 inches farther than the mound because they try to tunnel out under the coffee mud. The only thing I can figure is that they refuse to dig through the coffee, and when they can't go out and feed the mound, the colony dies. One way or another, it kills the mounds. This is hard to do when you collect your own grounds, bit you can get so much at one time at Starbucks when you go at the right time of day. Sometimes, I have come away with about 60 pounds of used coffee grounds when I ask them for the bag they are filling behind the counter. On another note, try experimenting with coffee repelling ants and other insects. Like if you had a small garden, you could pour a barrier of grounds around the perimeter of the garden to keep them away. The barrier would also keep out mealy bugs, scales, aphids, and even spider mites. I never got to finish a formal experiment, but I would bet money that used coffee grounds would get rid of chinch bugs in the lawn as well.