Mostly adult Lepidoptera feed on plant nectar. That is, adults can only contribute to carbon, and not nitrogen, acquisition. The moth Heliothis virescens were used to explore the hypothesis that larval nutrition influences various adult carbon pools and that these, in turn, may affect pheromone production quantitatively. H. virescens larvae were reared on diets differing in carbohydrate, fat or protein content and resulting 5 th instars and adults were analyzed for carbon pools, hemolymph trehalose concentration (HTC) and lipid content. Across all the diet treatments, changes in carbohydrate content affected carbon pool the most. In particular, for insects reared on a high carbohydrate diet, adults had a greater lipid content, while for insects reared on a low carbohydrate diet, adults had a lower HTC, compared to insects reared on the control or other diets. By contrast, changes in protein and fat had little effect on HTC and lipid content of adults.