Dave

Perhaps you had instant grits. We used Jim Dandy brand and it worked ever time. We lightly cover the mound and it looks like snow. Then stick holes all over the mound with a stick and the grits are gone within a day ot two. A few days later you can't find an ant anywhere in the mound and no new mounds seem to reapear any where around the area. I'm told they eat it and it swells up inside them or perhaps it dries them up.
Anyway the instant grits didn't work...they ate them and stayed till we used the regular grits and then Gone every time.

Used this in south Alabama...central Alabama and north Alabama as well as Columbus, Georgia. can't see how Texas fireants would be different.