In this study, potential of the entomopathogenic fungi (EPF) isolates from dead samples of Orosanga japonica (Melichar) (Hemiptera: Ricaniidae) was evaluated. Infected specimens with fungi results confirmed that the samples were Beauveria bassiana after morphological and molecular identification. Amplicons produced two haplotypes (h = 2), which included one polymorphic site after sequence and named isolates 1 and 2. Two haplotypes were rooted with MK229193.1, MG345084.1 B. bassiana Genbank samples. Two-year survey results of the EPF effects revealed the highest mortality and natural infection rates in the field. Natural mortality rates varied between 80.35% (Findikli-August) and 94.8% (cayeli-September) in 2018 and between 79.82% (Alipasa-August) and 97.75% (Findikli- September) in 2019. For nymphs, the lowest LT50 value was found at 2.92 days for isolate 1 and 2.56 days for isolate 2, with a concentration of 1 x 10(6) conidia/ml, using the leaf dipping method. For adults, the lowest LT50 value was found at 3.02 days for isolate 1 and 3.15 days for isolate 2, with a concentration of 1 x 10(6) conidia/ml, using the direct spraying method. Nymph LT50 values were found a little bit lower than adults. Direct spraying methods results gave a high LT50 value for nymph in contrast to adult. Although the LT50 ratios gave high/low degree in different isolates, methods and life stages, non-significant differences were found between each other's (p > 0.05). In general, B. bassiana natural infection rates were found high in August and September during the 2 years. Efficacy of the two isolates, which derived from naturally infected O. japonica specimens, increased with concentration. The two isolates can potentially be used for O. japonica integrated management, as a fungal biocontrol agent, but their toxicological effects on beneficial insects, such as honeybees, will need to be determined.