The diagnostics, ecology, damage caused and controls for the chief pests in herbaria are described. The effectiveness and safety of available pest controls are reviewed. It is shown that a number of chemical controls are less effective than widely believed while the hazards to health and herbarium materials posed by some may often be overlooked. Neither of the currently used specimen poisons, mercuric chloride and lauryl pentachlorphenate are satisfactory. It is shown that pest controllers should integrate chemical methods with safe and effective physical measures. These include having barriers to the entry of flying insects; treating incoming specimens with freezing, microwaves or aerosol insecticides; monitoring pest arrivals using baited traps; restricting breeding by having low relative humidity, dustless floors and sealed steel cabinets containing a fumigant; and periodic eradication by fumigation with methyl bromide.