Bean bug, Riptortus clavatus Thunberg (Heteroptera: Alydidae) causes serious damage to Leguminosae. Herein an entomopathogenic fungal virulence assay system against bean bugs was established to construct a fungal database which can be used in integrated pest management (IPM). First to obtain as many bean bugs as possible at the same stage, host plant-preference and developmental synchronization of bean bugs were investigated. In the preference assay, five pairs of adults were infested in a plastic cage, where a pot of green bean, pea or cowpea was previously placed. The highest fecundity and the fastest development of bean bug was observed in the green bean cage. Secondly, in the synchronization experiment, eggs were collected from the cage of adults in 1, 3, 5 and 7 days after oviposition and transferred to a fresh cage with green beans. From the every 4 days of survey, similar stages of bean bugs were found in the cages with the oviposition for 1 and 3 days, rather than the longer times of oviposition. A fungal bioassay against bean bugs was conducted using the bean bugs from the above insect rearing system. Ten Beauveria bassiana isolates were cultured on quarter-strength Sabouraud dextrose agar (¼SDA) for 7 days at 25°C. Ten 4th instar of nymphs were placed on a cultured plate for 1 hour and tranferred to a fresh moisturized plate with grains of green bean. ERL836 isolate treatment showed the highest virulence and fungal mycosis was observed on the bean bugs. In conclusion, these results can be useful to establish an entomopathogenic fungal database for IPM.