Life history and larviparous reproduction cycle of Musca bezzii Patton et Cragg were investigated. The duration of larval and pupal development was reduced as the temperature rose to the range of 15 to 30℃. Threshold temperatures of development were 4.8℃ for larvae and 8.4℃ for pupae. Effective accumulative temperatures in larvae and pupae were 101.5 and 187.0 degree-days, respectively. It was confirmed that the female adults deposit the late first instar larvae. Blood ingestion rate of the female flies in the field was very low (3.9%). In ovarian development, first the largest follicle in two pairs of ovarioles formed mature eggs in 5-6 days after emergence and the next one reached maturity in 8-9 days; then egg maturation alternately took place in the left and right ovarioles at 2-3 days' intervals. Ovulation also alternately occurred after completion of egg maturation. The eggs hatched in the uterus about 16-24hr after ovulation, and most of the first instar larvae (16-24hr) were passed within the uterus. Fertilized females collected in the field most frequently deposited the larvae at 2 and 3 days' intervals at 30 and 25℃, respectively. The physiological age of female flies was classified into 5 categories based on the number of follicular relics in ovarioles, developmental stages of follicle and uterus contents. In each category, the calendar age of females was calculated. It was suggested that the determination of the physiological and calendar ages of the female flies of M. bezzii in the field is applicable within the limits of the possible.