Borax or boric acid can kill termites but the problem is that they have to eat it in order to work. Borax disrupts their digestive systems. Termites primarily eat wood, unlike ants.Termite. And, agree w/ Casper’s Human: get a termite expert in. I’ve had good luck with Borite, I believe it was called. This disrupts the natural cycle of the termite and they didn’t come back. Also get rid of any damp loose wood under your house.
You can apply borax and it will work to kill the ones above ground but there will be many, many more, living below ground and inside your walls, that won't come into contact with borax and eat it.
Borax will kill off a few but there will be more that aren't killed.
BTW: Termites exist on all continents except Antarctica.