A stage-specific vertical life table of the aquatic beetle Berosus alternans Brullé was constructed based on a laboratory study. Embryonic development time was estimated as 3.5 days. Eggs hatched between the 4^th and 14^th days after being laid. Females constructed, on average, 2.46 egg cases per day during 84 consecutive days. The first oviposition occurred on the 6^th day after mating, extending until the 84^thday. The mean durations of instars and stages were: egg, 6.12; L1, 4.93; L2, 5.13; L3, 11.17; pre-pupa, 109.12 and pupa, 7.31 days. Preadult development time was completed in 127.6 days for males, and in 154.4 days for females. When we tested mean duration by developmental stages, pre-pupa was significantly longer for females than for males (P < 0.01). Relative mortality was highest in the third instar, followed by the pupal stage.