Borax (or sodium tetraborate) is a naturally occurring alkaline compound that is a precursor in the manufacture of boric acid. In the household, boric acid and borates as tablets or powder are used to kill insects. It is a frequent ingredient in soaps and detergents. It is used in conjunction with borax to buffer and preserve certain eye drops.

When they suggested borax they were probably talking about the powdered soap.

I had carpenter ants, both winged and no wings.  When we finally found the trees the nest was in, destroyed the nest and removed the trees as they were dead inside was the only way we finally got rid of them.

I used professionals to spray my house.