The term bibliophagous is applied to organisms (fungi, bacteria, insects, rodents, and man) that damage mainly paper, but it can be used in a broader sense for those organisms that deteriorate furniture, fur, paintings, or other stored things such as insect collections. The insects appear, proliferate, and are actually harmful when the environmental parameters such as relative humidity, temperature, temperature fluctuation, illumination, dust, and aeration are not adequate. On the other hand, these factors also act as deteriorators. Each kind of bibliophage produces characteristic damage, and studying this damage, as well as excrement, and powders, lead to its identification, even when it is not seen. The most common bibliophagous insects are: silverfish, book-lice, cockroaches, house moths, termites, and bookworms.