Water spots, have you ever noticed in your shower or bath that the water condensates on the ceiling. The steam build up and a water droplet forms much like a wet cave. These marks can be misidentified as termites, but they are just water which has dried leaving behind minerals. You might have to enlarge the picture to see what I’m talking about. I guess the take away is you need venting in the bathroom, that steam can cause a lot of issues. Water, steam etc can make drywall get moldy and damage the integrity of the product and even cause interior issues. Then if the water runs down the 2×4, termites may come up through the weakened termite barrier. Big problems, all caused by water – so think of those water spots as a alarm to open a window or turn that fan on.