Ants everywhere! HELP

[Henry Lazerow]

My 4 unit building has ants all over two of the units. They are in various spots on the floor and if dog food left out will swarm the dog food. We have not had any issues with pests other then the ants. Illinois very tiny ants. I have put on the plastic ant traps but these don't seem to be working. Brick building both on first and second floor and can't find anywhere from outside they could be coming in. Ideas? 

[Jeff Copeland]

This seems like a pretty routine problem. Why not just hire a pest control company / exterminator and spend your time on something more important?