Wolbachia, Rickettsia, Spiroplasma and Cardinium are endosymbiotic and intracellular bacteria known to cause numerous disorders in host reproduction, reflected in their common name “male-killers”. In this study, 297 beetle species from various taxonomic groups were screened with the use of molecular markers for the presence of infection by any of these endosymbionts. Wolbachia was found to be the most common “male-killer” among beetle hosts as it infected approx. 27% of species. Rickettsia, Spiroplasma and Cardinium were much less prevalent as they infected: 8%, 3% and 2%, respectively, of the studied beetle species. This is the first report of Cardinium presence in beetle hosts. Incidences of co-infection of two bacteria taxa were very rare and only two weevil species were found to be infected by three different bacteria. These findings suggest that endosymbiotic bacteria inhabit their host at various levels of prevalence and that particular taxa usually infect different hosts, suggesting some competition among “male-killers”. This is the first study that simultaneously verifies infection status by all major endosymbiotic bacteria in hundreds of species (based on coleopterans).