This general discussion on the injurious fauna to be found in libraries and other stores of books and archives (with particular reference to Italy) includes a section on insect pests of the orders Blattoidea (Dictyoptera), Thysanura, Corrodentia (Psocoptera), Isoptera, and Coleoptera. The distinction is made between insects habitually feeding on the constituents of books such as paper, parchment, leather, binding thread and adhesives, and insects feeding mostly on wood, textiles, or stored foodstuffs and only occasionally infesting books or documents if these happen to be near the normal habitat. Notes are given on the morphology and biology of each insect order (and in some cases of separate families within an order) and on the typical damage that it causes. Attention is drawn to the fact that termites and anobiid and lyctid beetles may cause primary infestation in wooden furniture or shelving in libraries and spread secondarily to books and documents on them, and to the increased risk of this in recent years owing to the installation of central heating in libraries. The biotic agents, the damage caused by them, and the environmental conditions favoring them are summarized in tabular form.