Fire ants in exterior walls

[AskHarris]

In several places around the exterior of our home, my wife and I have found fire ant trails leading inside the brick walls, through the ventilation gaps and holes in the mortar. We know we have a large population under our sidewalks, cement porch, and foundation. Now we're afraid they'll be moving inside with us. Twice before we've had them following plumbing lines inside. Then we had an exterminator use a "low-impact" treatment, using mostly pyrethrum. Each time we find a mound, we drench it with Compost Tea we get from an organic nursery. That stops them from using that particular entrance, but they usually will just move down to another. What else can we do? What if there is already a large population inside out walls?

[Mr. Clean]

I don't think it is that uncommon to find the ants forming an ant line or building tunnels up to weep holes or other entrances into the home. I often find them trying to move in. I keep a spray bottle of orange oil and water for general wipe down around the house. I simply spray them down. I haven't noticed any ant invasions inside the house. They might be inside the exterior walls, but for now they are out of sight and out of my mind. :) I think you are doing just fine treating the mounds as they appear.