They haven't given up, merely just regrouping.
I laid down boric bait only a year later to find ants wandering my home with a distinct boric acid smell on them.
This is the only stuff that truly works in a wide variety of situations...
http://www.homedepot.com/p/AMDRO-24-oz-Ant-Block-Home-Perimeter-Ant-Bait-8150490/100598633
