I have never thought about ants; we don't have much of a problem with them, here. You know, they could be a problem if one's fermentor bucket is not sealed completely. I just leave my lid setting loosely for the first week or so.
They don't like to cross water, so maybe put your fermentor bucket in a small tub of water; it only has to be a quarter inch deep.
Or you could buy one of the thin, clear, plant water protectors, which you put under potted plants so they don't leak on the furniture when you water. I think you might be able to get one large enough to hold a fermentor bucket. You could put a littl kmeta or StarSan in it; I know they would not cross through it.
(Wal-mart)