The calliphorid Cynomya mortuorum (L., 1761) is a species of forensic interest, present mainly in the Palaearctic Region. Nearly nothing is known about its life history. We provide here the first data regarding pupal weight evolution during the pupal stage, female fertility and life expectancy of the species. At 22°C under a variable regime of temperatures, the egg-to-adult development time was an average of 18.05 ± 0.72 and 18.47 ± 0.67 days for females and males, respectively, in the control group. The pupal stage represented 56.7% of the total development. The development time from egg to adult and the duration of the pupal stage were significantly longer for males than for females. The measurement of pupal weight at the start of the pupal period revealed that female pupae were significantly lighter than male pupae by nearly 20%. This difference between the sexes was also observed for the dry weight of adults. An average decrease of 8.75% was observed throughout the first 8 days of the pupal stage, after which most adults started to emerge. The tested females produced an average of 176.13 ± 66.62 eggs throughout the egg-laying period. The average lifespan after emergence was 12.10 ± 4.09 days for females and 12.60 ± 2.95 days for males, with a median of 12.50 days for both sexes.