If ants can get in from outside, so can the cold winter (and hot summer) air. I followed the ants for a few day and figured out how they got in — there were a few rather significant cracks. So, I used the ants to find the leaks I should have caulked last fall.
The ants are still happy and doing their thing … except now, outside. Our house will be warmer next winter and cooler this summer. No trucks loaded with chemicals came by our house.
(Via What's On?.)