Carotenoids in 38 species of Lepidoptera have been examined qualitatively and quantitatively. Comparisons are made between cryptic and aposematic species, pupae and adult, dried and fresh material, males and females, and certain polymorphic species. Although some selective storage is demonstrated, Lepidoptera chiefly store the carotenoids present in their food plants unchanged. It was found that the Large White (Pieris brassicae), a toxic species, stored more carotenoids than the less toxic Small White (P. rapae) while ab. coerulea (P. brassicae) contained only 25 % of the carotenoids found in typical specimens.