I own a Nuisance Wildlife Control business for the past 23 years. It is true about the plastic on wiring being vegetable based now. It used to be petroleum based years ago and we never had problems. Now I get calls all the time about wiring damage. Especially the wiring in your house. Squirrels love it! If you think you have squirrels in your attic, get them out ASAP!
As far as the mothballs and lights as a deterrent, that’s all B.S. It might make you feel better that you’re trying something but it doesn’t do a thing. You need to remove them from the area whether you use traps or poison. Keep mice traps set all the time in areas you might have mice. That’s the best way to prevent problems. If you don’t have traps set, by the time you realize you have problems, it’s usually too late. The good ol Victor snap traps will out catch all others 10/1.