The effect of a water extract from Hyoscyamus muticus upon Musca domestica was studied. High percentage of larval mortality was obtained when early 3rd larval instars were treated. The treatment of late 3rd larval instar caused high mortality during the pupal stage. Treatment of early and late 3rd larval instars had shortened their larval duration than in the check, with no significant effect on the pupal period. Fecundity of females that resulted from treated larvae was reduced. Mortality in adults was 20% when treated with 100 μg|insect.Female and male longevity were shortened than their respective control. Significant prolongation in the pre-oviposition period reduction in oviposition period and highly significant reduction in fecundity of treated female had occurred.