Hi Keiko!
 
Ants HATE peppermint scatter some leaves around the ferrets cage, on your
carpet etc.  They are very effective.  I've also heard peppermint oil has
the same effect but I've been afraid of its concentration as far as the
fuzzies are concerned, and I've never gotten a good answer one way or the
other to say if it is good or bad for them.  You might also try the
peppermint oil at the outside spot where the ants are coming in.
 
Karla
[Posted in FML issue 2559]