The bean bug, Riptortus pedestris (Fabricius), is a serious pest of legume crops in East Asia. Here, we report how the consumption of different types of legume seeds affects various aspects of nymphal and adult traits related to fitness in R. pedestris. Two experiments were conducted. In the first experiment, we assessed how R. pedestris nymphs and adults performed on one of 10 different legume seeds: adzuki bean, chickpea, cowpea, two kidney bean varieties (red, white), mung bean, peanut, small black bean, and two soybean varieties (black, yellow). Riptortus pedestris fed on yellow soybean and chickpea performed well in terms of nymphal survivorship and fecundity. However, R. pedestris fed on two kidney bean varieties suffered 100% nymphal mortality and reduced fecundity. Small black bean and black soybean supported high fecundity, but were not suitable for nymphal development. Lipid content was 4- to 11-folds higher in R. pedestris raised on peanuts than those on the others. In the second experiment, we recorded the key parameters of adult performance from R. pedestris assigned to one of nine combinations of three nymphal and three adult diets (yellow soybean, adzuki bean, peanut). Riptortus pedestris raised on yellow soybean during development produced more eggs over their lifetime than those raised on the others. However, this beneficial effect of consuming yellow soybean during development occurred only when yellow soybean was consumed during adulthood. Our data have implications for predicting the occurrence and population dynamics of this pest.