A tiny ( under 1 mm ) , soft-bodied wingless psocoptera ( usually Trogium pulsatorium ) . The insect actually feeds on molds and other organic matter found in ill-maintained works , but they will also attack bindings and other parts . A tiny ( under 1 mm ) , soft-bodied wingless Psocoptera ( usually Trogium pulsatorium ) , that actually feeds on microscopic molds and other organic matter found in ill-maintained works ( e.g. , cool , damp , dark , and undisturbed areas of archives , libraries , and museums ) , although they will also attack bindings and other book parts .