Water damage by far is the most destructive thing in a house. There is no way that ignoring it is correct.
You can fight the ants all you want, but you'll still get mold, and rot, and eventually have to replace the beams (if the water has been there longer than a few weeks then replacing the beams is almost a given). The ants are the least of your problems.
I never said ignoring it was correct. I said that it is not always possible to take care of the problem immediately; cash and time are finite resources for me, plus I cannot control the weather. I'm saying after you fix the problem (or in the interim) break out the Terro Gel and dose the little sappers with boric acid.
If you think a few weeks of water damage warrants replacing the beams I am afraid you were ripped off by a contractor. Speaking from personal experience there was a leak in the bathroom when I bought my house that had been there for not a few weeks but many weeks. I ripped down the moldy sheetrock, fixed the pipe and let the joists air out. Sure there is water staining on the joists, but they are 8x2 oak joists (1929 lumber when dimensions were real) and the joists were dry by the time I had taken down all the old plaster and lathe in the dining room. When I buttoned up the ceiling they were dry and stiff enough that they offered significant resistance when I screwed in 2 inch drywall screws.
You can fight the ants all you want, but you'll still get mold, and rot, and eventually have to replace the beams (if the water has been there longer than a few weeks then replacing the beams is almost a given). The ants are the least of your problems.