UG! In our last house we had a Carpentar Ant problem that was SOOOO bad - I would find them ALL over my toilets and at one point there were falling from my recessed lights in my KITCHEN and would drop on my counters, on my table - while we were eating - YUCK!
First course of action is to THOROUGHLY investigate your house from top to bottom - they typically enter the house where there is a moisture problem. For us it was where the Garage roof met the side of the house - we repaired the damage and caulked any other suspicious spots, ripped out and replaced any rotted wood outside and also ripped out all the caulk in our bathrooms and recaulked everything - the toilets, tubs, showers etc. Then we hired an exterminator company and had them come quarterly - in addition we supplemented with spray purchased from HD that we used only outside - for our wooden retaining wall, we'd spray the outside of the house, spray the garage roof, the deck etc.
If you are VERY active and progressive you can find a way to fix the issue. You REALLY have to be thorough with the outside of your home though - inspect EVERYTHING to make sure it's not damp and rotting etc. GOOD LUCK!