Somewhere on here I have some pictures of my Davis infested with ants, (for the 2nd or 3rd time BTW). But, it sounds like you have a more aggressive, wire-chewing type ant. Once I cleaned and fumigated the station, it was OK.
We were also wondering if we get more ants in dry years. For us, it has not been increasing really; just varying from year to year.
Last week I used Bifen IT insecticide around the house and an ant hill, and it stopped them cold. I've been using Bifen primarily for tick management, but am finding that it is one of the most effective things I've ever tried. Only a small application was needed. Otherwise, I use a Borax type powder.