Ants and mice infestation, help!

I have a problem with ants and mice who have infested a barn. I built a bedroom within it, unfortunately a guest who was using the room frequently left food lying about and I have not been able to get rid of the ants since. I’ve tried commercial traps and making my own poison with boric acid but it’s not working. I removed a 4 meter long section of the nest but there’s more of it in an inaccessible area.



Any tips please, it’s getting desperate!



Thanks



James

Get an Anteater? Sorry James - I’m not sure what’s worse Ants or Rats???