Insect Damage
Medieval books were typically bound with wooden covers. This wooden cover and the parchment pages within have been eaten away by insects. This weakens the wood and parchment in some areas and removes original content. These pests, which commonly include silverfish and beetles, live on the starches and proteins in the wood, parchment, paper and adhesive of books. They can be very difficult to eradicate once they infest library materials.