Abstract: Wireworms, the polyphagous larvae of click beetles belonging to the genus Agriotes(Coleoptera: Elateridae), are severe and widespread agricultural pests affecting numerous cropsworldwide. A previously unknown intracellular bacterium has been identified in a diseasedAgriotes larva. Microscopic studies revealed the subcellular structures characteristic ofrickettsiosis. Molecular phylogenetic analysis based on 16S ribosomal RNA encoding rrs genedemonstrated that the wireworm pathogen belongs to the taxonomic genus Rickettsiella(Gammaproteobacteria; Legionellales). The pathotype designation `Rickettsiella agriotidis´ hasbeen proposed to refer to this organism. Moreover, genetic analysis makes it likely that this newpathotype should be considered a synonym of the nomenclatural type species, Rickettsiellapopilliae.