Here are some more ideas.

http://ipm.ucanr.edu/PMG/GARDEN/CONTROLS/antmanagement.html

You need to get some professional products that will form long lasting, non-repellent barriers and gel baits that ants will bring back to their nests and kill the queens. Fipronil, Abamectin, Imidicloprid, Bifenthrin and Permethrin. One year, after wildfires came very close and we were evacuated, we came back after a week and there were swarms of ants all over my house crawling up walls in streams 4 inches wide, in the bathrooms, on kitchen counters, in my cabinets, everywhere. They came in to escape the heat and approaching fire. We had an exterminator out about 6 times but after two months with swarms of ants still crawling across the walls, we had to take it into our own hands. We did a massive assault with baiting and spraying with variety of targeted professional products OUTSIDE and to a esser extent, some bait and gel inside. First we created a barrier around the house foundation to keep them out of the house, then moved outward until we reached the property line, and made another barrier around the perimeter of our yard. It was so bad, it really came down to us or them and we had to win. Took about two months to fully knock them down. That was in 2007. I have not seen a single ant inside and very few outside since then. A few boric acid baits or a little spot of gel applied by the exterminator would never have been enough. I think they only want to kill enough ants to make you believe they are doing something, but leave enough that you keep having them back every month to spay your kitchen and bath baseboards.