That makes me think that the ants are attracted to a certain environment. Probably where it is dry and disturbed. I did this treatment to kill off the nests near to the house, but the only long term solution is to eliminate their environment. I did this by letting the wild grass and flowers take over those areas of the yard. I'm not sure if it is the moisture they trap, or the other animals they house, but the ants don't have success colonizing these more healthy ecosystems. Good luck!