Abstract
Libraries are invaluable resources, documenting significant events that have shaped human history. However, the preservation of old books is severely threatened by insects commonly referred to as bookworms. In this study, a sample of infested books in a historic library in Taiwan was randomly selected and examined. An anobiid book-boring beetle, Falsogastrallus sauteri Pic, 1914 (Coleoptera: Ptinidae) was identified as the major bookworm species present. To facilitate its identification, both adults and larvae of F. sauteri are redescribed, with emphasis on its ultramorphological characteristics as revealed by scanning electronic microscopy. Furthermore, an undescribed parasitoid wasp in the Bethylidae was discovered in the frass, holes and tunnels created by F. sauteri. The new species, Cephalonomia formosiensis sp. nov. is described, and we suggest that it probably uses F. sauteri as host.