That is a bummer! Sorry to hear it, yet pleased you brought the subject up. I had the same thing happen to me a few years ago, and also lost a lot of material. The critters even ate the squirrel tails off of some of my Mepps spinners.
I agree that the stuff should be inspected regularly. The Moth Balls are a great solution, but do not assure the stuff is safe forever.
I think I did much the same in the cleanup as you, but went one step further. Every piece of material is now in it’s own zip lock bag. The bags are stored in a large plastic container, with a tin (perforated) of mothballs. That keeps the moths away from the materials, and prevents the materials from smelling like mothballs. The smell gets old after a while, and is not the healthiest stuff to breathe.
I found the different sized zip-locks by searching ebay. It cost me a few bucks to get all the different sizes I needed (generally only sold in bundles of 100), but considering the value already lost, it was cheap protection for the future.
One final thought. Do not consider any item purchased to be “clean” and safe. Consider it contaminated, and keep it in it’s own bag.
Here is a link to the probable critter causing the problem if anyone is interested in more info: