i had ants in my lang hive most of the year last year with no problems. i also have ants in two of my top bar hives this year. from what ive seen the ants just want the debris on the bottom, so i dont mind them, and the bees dont seem to care either. ofcoarse it depends on the kind of ant too. im in maine and just have medium sized black ants which aren't much of a threat. if i had nasty ants around id put each leg of the hive in a can of oil or some other nasty liquid. you know a little moat for the bees.