In hymenopteran societies, workers are not always sterile, and may produce parthenogenetically either males (arrhenotoky) or females (thelytoky). Thelytoky however is exceptional, and has been recorded in only four ant species. Here we provide evidence for worker thelytoky in an additional species, the harvesting ant Messor capitatus (Latreille) (Hymenoptera Formicidae Myrmicinae). Two orphaned colonies produced a large amount of worker offspring during 10 months in the laboratory. Dissections showed that reproduction was performed by workers and not by mated worker-like individuals (ergatoids). In some pararsitoid wasps, parthenogenetic reproduction is caused by the maternally transmitted bacterium Wolbachia. Using a PCR-based assay we showed that Wolbachia can not be involved in parthenogenesis induction in this species. Finally, we point out reasons for the low Wolbachia susceptibility of parthenogenetic ant species.