Yes, termites supposedly chew through liners to get the water during droughts - you'd think they'd evolve and do the simple thing - climb the wall and go over, but unfortunately, they prefer to go in from underneath, break through and die in a scale flood bigger than what Noah experienced. Dumb things.....
If termites are a problem in your area, You can treat for termites around your pool yearly, but I really don't think another layer of foam plastic will stop them if they're willing to eat through vinyl to get at your water.....