Survival data of mosquito males and females under different dietary conditions but constant antecedent and con-temporaneous environmental conditions are presented. Two strains of the yellow fever mosquito Aedes aegypti (L.), a strain of the subspecies Culex pipiens fatigans Wiedemann and an autogenous strain of C. p. pipiens L. have been compared. Mean survival time and 50% survival time are considered to be more representative than maximal life-span. Survival under complete starvation was significantly prolonged by feeding sucrose in all experiments, but less by feeding protein alone. In general, optimal survival was observed when males were fed on sugar and females on sugar and protein. Autogenous females of C. p. pipiens showed reduced survival upon regular blood and sugar feeding after their first gonotrophic cycle.