The effects of different temperatures and diets experienced during distinct life stages are not necessarily similar. The silver-spoon hypothesis predicts that developing under favorable conditions will always lead to better performing adults under all adult conditions. The environment-matching hypothesis suggests that a match between developmental and adult conditions will lead to the best performing adults. Similar to the latter hypothesis, the beneficial-acclimation hypothesis suggests that either developing or acclimating as adults to the test temperature will improve later performance under such temperature. We disentangled here between the effect of growth, adult, and mating conditions (temperature and diet) on reproduction in the red flour beetle (Tribolium castaneum), in reference to the reproduction success rate, the number of viable offspring produced, and the mean offspring mass 13 days after mating. The most influential stage affecting reproduction differed between the diet and temperature experiments: adult temperature vs. parental growth diet. Generally, a yeast-rich diet or warmer temperature improved reproduction, supporting the silver-spoon hypothesis. However, interactions between life stages made the results more complex, also fitting the environment-matching hypothesis. Warm growth temperature positively affected reproduction success, but only when adults were kept under the same warm temperature. When the parental growth and adult diets matched, the mean offspring mass was greater than in a mismatch between the two. Additionally, a match between warm adult temperature and warm offspring growth temperature led to the largest offspring mass. These findings support the environment-matching hypothesis. Our results provide evidence for all these hypotheses and demonstrate that parental effects and plasticity may be induced by temperature and diet.