Shows how materials and ambient conditions found by accident or design in libraries and archive stores (such as dust, insufficient ventilation, inappropriate lighting, high temperatures, high relative humidity and materials attractive to pests used for the manufacture or restoration of books) can favor attacks by insects and other microorganisms, and how modification of them can help to prevent it or to check existing infestations of each type. The solid, liquid or gaseous formulations of chemicals most appropriate for application against lepismatids, cockroaches, psocids, or wood-boring insects such as termites and anobiid or lyctid beetles are shown in tabular form, and also the effectiveness against insects, fungi, and bacteria and any adverse side-effects on the books of three commonly used fumigants (methyl bromide, formaldehyde, and ethylene oxide). Attention is drawn to the necessity for the chemical control of library pests, of using materials that are neither toxic nor repellent to man nor harmful to books or documents.