Keep to the same check list we discussed earlier in checking pipes and cracks in the area between the floor and walls. These ants are probably living near a heat source such as a refrigerator or water heater so treat those areas nearest to the ant movement and that heat source.
An ants normal habitat would be to hibernate, so if we see activity there has to be heat fooling their natural senses. A warm home or crawl space can easily do that. However they are going to focus in the heated area and not travel out of it.
Baits are still best in this situation in that the nest is often very hard to get to if it is behind the wall near the stove or something similar.
