A local do-it-yourself pest control place told me that if you do a
trench and fill termite treatment around the perimeter of the house,
cutting the termites inside the house off from the outside, any
termites inside will die out. Does this sound correct?

Thanks for all input.
yes that right, but what if they get up to the attic and get water from
the moisture that comes off the a/c unit.. then you never get to them...
better call out a licensed termite man to take care of the problem... it
will cost you more in the long run.. and just because you get a lic.
termite man does not mean the problem will go away.. i had one flood the
exterior of a gargage i built in the back yard.. termites came back..
and back and back.. he came out each time and did the flooding, but it
was not doing any good... i then went to home depot when you could still
buy dursban there and sprayed it and they never came back. that was
about 10 yrs. now.. i know that dursban does not last for ever either so
i give it another spray ever other year for good luck and so far no more
termited.....