Leaf cutter ants are my nemesis. I've DE'd their nest so many times, but they must have a HUGE colony. They just move the entrance/exit somewhere else. I won't use pesticide because it affects too many other wildlife that I want around, but I'm so, so, so very tempted. They've striped much of my yard this year, some vegetation to the point where I'm not sure they'll recover. Frustrating!
The regular little red ants are also everywhere! DE seems a tiny bit more effective on them.
We're both in the same boat. If someone out there knows of an effective way to deal with them without going nuclear, please let us know.