Two egg parasitoid species, Telenomus nawai and Telenomus spec. are similar morphologically but they have been treated as different species because of their different reproductive forms, arrhenotoky and thelytoky. Male progeny were produced from the thelytokous colony of Telenomus spec. (TT) by heat and antibiotic treatments. These males mated successfully with females of arrhenotokous colony of T. nawai (AT) and the females produced on average 19.1% males. This percentage did not differ from that obtained from AT females mated with AT males (19.4%). Diagnostic PCR indicated that TT is infected with Wolbachia; antibiotic treatments eliminated Wolbachia from TT. These facts suggest that Wolbachia causes thelytoky and Telenomus spec. (TT) is conspecific with T. nawai (AT).