In my house,they come in through the windows and Patiodoor.
There are small openings at the bottom of the windows for water to escape,a great door-way for the ants,the same with the patio-door.
So far,I've used chalk-lines at the doors and baby-powder in the windows,vinegar at the patio-door,it seems to be woriking,only had 2 ants at the kitty food dishes