Hi all!  I too just recently had ant problems above the inner cover.
I went to the Indiana beekeeper assoc. meeting a month ago and asked
how to get rid of the ants....well, I got several different answers,
but they all claimed they worked for them. I was told to pick what
was comfortable and go with it.
 
Sprikling comet was one.  Ant poison was another (I did not do this one).
Another was proping up the telescoping cover from the inner cover with
little sticks (the ants like the tight space), and, lastly, sprinkling
Diatomaceous Earth or Celite on the inner cover. The last is good for
slugs in the garden too!
 
For me, ended up changing covers and moving my bees to my new farm!
Peace,
Mike Quimby....hoping to expand next year with 2 recently discovered
               bee trees! (if they swarm)
 
From: QUIMBY MICHAEL E              (MCVAX0::RK81239)
 
To:   FOREIGN TRANSPORT ADDRESSEE   (MCDEV1::IN%"[log in to unmask]")