Hi Jackie,
 
We get a lot of ant infestations too, usually after the rainy season when
the colonies are looking for a nice dry spot.  We are usually able to get
rid of them within a day or two of careful observation and treatment.
 
I'm sorry to hear that you weren't able to find the point of entry,
because that is always the first thing we do before trying to fix the
problem.  One trick is to pick an individual ant and watch it for a long
time.  If it's following an established trail then you will notice other
ants passing it in the other direction.  This works best when the ant
population is fairly heavy and hasn't been disturbed for a while.
(Scrubbing the floor with vinegar probably removed their trails and
forced them to run around randomly for a few hours trying to find new
ones.)
 
After finding the point of entry, we try to just caulk it up if it's a
small, well-defined hole.
 
If that doesn't work then we look for where the trail is coming in from
the outside and sprinkle some diatomaceous earth across it.  Diatomacous
earth is an organic pesticide that kills mechanically rather than as a
poison.  On a microscopic level the dust particles are very sharp and cut
the ants' feet if they walk over it or cut up their insides if they eat
it.  From my experience ants don't want to get anywhere near the stuff
and are loathe to cross over it.  It is supposed to be safe for use
around food, although we personally have never tried using it indoors.
 
If none of those solutions are possible then we pack up the ferrets with
their food and water and move them to another room of the house for a few
days.  If necessary, we put down some heavy-duty ant baits along the
path, but only when we are absolutely sure that the ferrets won't come in
contact with the bait or the ants who are carrying it.
 
Good luck, and I hope your little visitors will soon find a new home.
(The ants, that is, not the ferrets.)
 
Julie
[Posted in FML issue 5215]