Carpenter ants are wicked invaders. I wasn't implying that caulk would kill them, but it may eliminate the trail(s) they are using to find their way into the house. I did it successfully, so my experience is my guide in the advice I proferred. Additionally, if you find them in your yard, you can apply the toxins at that location, rather than in the home.
Once they are inside, it's too late for proactive measures like caulk, and you are forced to become reactive.