We've been having them here in Pa too. It's a bad year for them here. They are the black (carpenter?) ants, the big variety. Some up to 3/8" long (or 9.5mm for my European friends
). I have the little poison traps around.
Also, I've been spraying the perimeter of the house (especially thresholds like doors, the garage opening, etc) with a double strength mix of insect killer dispensed from my handy dandy pump sprayer.
It's helped keep them at bay mostly, but the little bastages just keep coming back. I don't know what the heck is so interesting in my house that they keep inviting themselves in.
They are a pain in the a$$ though that much is for sure.
If you don't already have one, get a pump sprayer and start on the outside of your house as your first line of defense.