The ants make their way up from the ground. The best way to stop ants from getting into your colony is to block them from being able to walk up the stand. The way I do it is to put small wooden blocks and large cans with a little oil in them then I lift my colony and place it on four blocks, all set up the same way. The ants will try to crawl up the side of the can, down the inside, and come up against the oil, they will not get past the oil.
