Answer: You can try diatomaceous earth, I have heard success stories in treating ants with it. Diatomaceous earth is available from Gardener's Supply Co. (www.gardeners.com or ph# 800-863-1700). I was going to suggest you pour boiling water down the hole of their hill but you mention you can't locate it, so that's a no go. If you do find it, try that. Folks have also had success with boric acid bait. A good "home remedy" is to make a paste out of sweetened condensed milk and boric acid powder. Roll into little balls (shoot for consistency of fudge). Place these about the garden and ants will eat them, share with their pals, and die. Be careful with this remedy if you have pets or children, they could eat the "fudge" as well. There's also an Insect Growth Regulator (IGR) for ants that breaks the reproductive cycle of certain species of ants. Check with manufacturers to see if there is one for the pest species in your yard (Zoecon Corp., 12200 Denton Dr., Dallas TX 75234; ph# 800/527-0512).
The problems with so much spraying of pyrethrins is that it is a broad-spectrum insecticide, and, as with other poisons, the target insects may develop a resistance. I hope a combination of approaches like the ones mentioned above will do the trick! Hang in there!
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