I think Mike pretty much summed it up there ^^^^. Diazanon is some good stuff. Dursban used to be the stuff until the EPA noted that the stuff was showing up in small trace amts in our water supplies. I'd also recommend Malathon (or Malathion sp) for grub worms, etc... I bought the concentrated stuff that you can mix w/ the Diazanon for the end of a sprayer. Be careful though. You don't want to conentrate that mess in one spot. It'll burn your yard while it's burning the bugs. The best time to put the stuff down is 2-3 days before a good raining. I ALWAYS check weather.com for those anticipated days.
I <b>had</b> this problem w/ grub worms/and a mole for a while and didn't know it (brown patches and spots in sparse places in the yards). Jokers were eating the roots of the bermuda and augustine <b>AND</b> this one tree. Tree had dying limbs over the last few years and I couldn't figure out why until ChemLawn brought their pesky arses over and dropped an offer to me. A 55$ per month offer to keep fertilizer and bug killers (MAINLY grub worms since they'd noted it) on my stuff. I got pizzed that VERY day and did Home Depot for 120+$ worth of chemicals. There are so many chemicals in my yards now until even passerbys w/ their dogs won't stop and pee on my mailbox anymore because it smells like a chemical plant. :emlaugh: No more grub worms, no trace of ants, hopefully no underground termite colonies, no more moles, no fleas, no mosquitoes, no more pizzing dogs :emlaugh: ... nothing. The towns' water supply rating should drop dramatically due to what I've done. LOL
That Diazanon and Malathon (sp) should keep the ants away for a very, very long time. Another thing, don't forget to treat during the winter months too. It'll prevent a spring/summer infestation.
Good luck all.