The ants invade every summer. There are a few scout ants (literally two or three) in almost every room of the house (old california house). If there is any food left out, or dog food left in the bowl, etc, the scouts call out a million troops. I doubt you have that kind of problem in Canada. They come up through the cracks in the floor boards, or from cracks in the corners of the rooms (we have wood flooring). Or else they find another way, I've seen them come in through teeny slits next to the screen frame in windows. I've had ant problems in the summer in every house I've lived in. All you can do is either use poison, or just make sure that nothing that will attract them is left out. They are wicked, and not in a good way.
"Space. It seems to go on and on forever. But then you get to the end and a gorilla starts throwing barrels at you."