Honeybee (Apis mellifera) is an important element of biodiversity and terrestrial ecosystems. Any pathogenic infection in this beneficial insect can lead to major undesirable disasters. In this study, we investigated the pathogenic bacterial and fungal potential of Polistes dominula and Polistes nympha (European paper bees) wasps and the insecticidal effects of these pathogens on honeybees (Apis mellifera). For this purpose, bacteria and fungi were isolated from dead and diseased bees collected from Terme district of Samsun province in Turkey in May and June 2020In the study, diseased and dead Polistes dominula paper wasp adults were identified as Serratia marcescens (no. 1), Enterococcus faecalis (no.6), Staphylococcus xylosus (no.9), Sphingomonas paucimobilis (no. 11), Staphylococcus lentus (no.13). ) and Candida ciferrii (M2) fungus were isolated. Granulicatella adiacens (No. 2), Staphylococcus xylosus (No. 10), Sphingomonas paucimobilis (No. 15) and Cryptococcus laurentii (M1) and Candida famata (M3) bacteria from the internal tissues and organs of Polistes dominula paper wasp adults (Debaryomyces, Fungi (also known as Hansensis and Torulopsis candida) were obtained. Staphylococcus xylosus and Sphingomonas paucimobilis were found to be common bacteria in both bee species. Serratia marcescens and Enterococcus faecalis bacterial species were found to have a very lethal effect on honeybees. Bioassay experiments were performed on the detected fungi, and it was observed that Cryptococcus laurentii and Candida famata fungi species also had lethal effects on honeybees. It has been revealed that entomopathogenic bacteria, which are known to be very effective in biological control against harmful insects, can cause unwanted infections in honeybees.