Many herbivorous insects feed on plant tissues as larvae but use other resources as adults. Adult nectaring is an important component of the diet of many adult herbivores, but few studies compare adult and larval feeding for broad groups of insects. We compiled a dataset of larval host use and adult nectar sources for 995 butterfly and moth species (Lepidoptera) in Central Europe. Using a phylogenetic generalized least squares approach, we found that Lepidoptera that fed on more plant species as larvae were also nectar-feeding on more plant species as adults. Lepidoptera that lack functional mouthparts as adults on average used more plant species as larval hosts than Lepidoptera with adult mouthparts. We found that 54% of Lepidoptera include their larval host as a nectar source. By creating null models describing similarity between larval and adult nectar sources, we furthermore show that Lepidoptera nectar on their larval host more than would be expected if they fed at random on available nectar sources. Despite nutritional differences of plant tissue and nectar, we show that there are similarities between adult and larval feeding in Lepidoptera. This suggests that either behavioral or digestive constraints are retained throughout the lifecycle of holometabolous herbivores, affecting host breadth and identity.