Abstract: Rhodnius prolixus Stål (Reduviidae: Rhodninii) is one of the most important vectors of Chagas disease. As a result of its medical importance, several life history studies have been carried out, but in general with a restricted demographical scope, without assessing the potential tradeoffs in the life history of this insect. In this study, individuals of R. prolixus were kept in two spatially different habitats and several fitness components were measured. The results show that life expectancy in adults is negatively correlated with gross fecundity, indicating a cost of reproduction. Life expectancy is shorter for males and longer for individuals of the same sex in the more complex habitat, where the fitness is lower compared with that of the simpler habitat.