Alright, so we are trying to word our invites and I'm not quite sure how to say that we aren't inviting our friends lovely spawns.

It's not that we wouldn't love to have them there; but our venew is also our caterer and we don't really want to pay per plate for some of the children. Also, we want people to stay late and we feel that if they bring their kids; they will be prone to leave earlier. Can anyone suggest a polite way to tell people that their kids are not invited?