Shelby gave you some good advice, but I wanted to add that one of the insects that eats horn is the kitchen moth, which is a small tan moth that often comes into homes by way of food that is carrying the eggs. Many people have seen them in their kitchens, but sometimes have difficulty finding the source. Usually it is an old box of cereal or meal at the back of the cupboard, within which you might find remnants of tiny spider-web-like cocoons, and sometimes the actual moths as well. These can be there even in a perfectly dry home. The moths themselves don't eat horn, but the larvae will. To stop the infestation, you of course need to get rid of the meal or whatever it is that they have infested, but it's also helpful to set traps for them, to catch any that are still around. Walmart sells pheromone-based sticky-board traps for these pest.
My most recent unpleasant experience with them was when my dad kept a bag of raw peanuts in his home office, and the moths hatched out in droves. They found their way to two horns I had made for him that were hanging on the wall. Dad likes to keep snacks out there, and this is the second time moths have damaged those same horns. Moth damage can be repaired with epoxy, colored with artist chalk to match the color of the horn, but it's a time-consuming chore. Best to keep out the moths.
