AbstractByturus tomentosus (raspberry beetle) and B. unicolor (raspberry fruitworm) are important byturid beetle pests of raspberry in Europe and North America, respectively. These pests are controlled by the application of insecticides. Developing alternative control measures requires knowledge of the relationships within and between these pests and similar organisms found in natural and agricultural situations. DNA analysis is the most direct method of studying genetic material that is possible and, in contrast to morphometrics, it is independent of life stage and any environmentally mediated variation. Here, we studied Byturidae (Coleoptera) interspecific relationships using nuclear ribosomal ITS2 and mitochondrial cytochrome oxidase [cytochrome-c oxidase] DNA sequences. Phylogenetic trees based on the mitochondrial and ribosomal sequences were generated. There was evidence that the raspberry fruitworm, B. unicolor, is divided into at least three distinct groupings. The American species was not the most related to the European raspberry beetle. Instead, links between B. affinis from Japan and the American beetle suggest that this lineage originated in Asia and colonized the western USA. More than 99% of UK B. tomentosus individuals are infected with the bacterial endosymbiont Wolbachia. In other arthropods, this group of bacteria is known to alter host reproduction by inducing parthenogenesis, feminization of genetic males, son killing and cytoplasmic incompatibility.