We investigated the intra- and trans-generational effects of larval diet on immune function, body size and development time of the greater wax moth, Galleria mellonella (Lepidoptera: Pyralidae). We found that moths reared on a diet diluted with cellulose (a low-nutrition diet) were about one-third smaller, had about one-fifth longer development time and exhibited about 10% stronger encapsulation responses as compared with moths reared on the standard diet. The low-nutrition parental diet prolonged the development time of male offspring that were fed the low-nutrition diet by about 4% and the development time of female offspring that were fed the standard diet by about 1%. However, females that were fed the low-nutrition diet attained about 6% greater body mass when their parents were reared on the low-nutrition diet. Our results add to the growing number of studies demonstrating that the nutritional history of parents can affect the performance of their offspring.