When I had problems with ants attacking and eating my bees, someone here suggesting painting one side of a piece of plywood with vaseline. Put the plywood (vaseline side down) under your bottom board (and on top of whatever you are using for a stand). The dry side of the plywood is up so the bees can use it as additional landing space, but the ants won't want to walk through the sticky stuff on the bottom side of the plywood to get to the hive. I tried this and it worked really, really well.
I know many folks use cans filled with oil (one can or each stand leg) with success. I does the same thing by making a barrier the ants don't want to cross. The draw back is that if it rains a lot, the cans can overfill, leaking oil onto the ground.
Whatever you use that ends up working, let us know. I think we all have this issue from time to time!