Morphological, cytochemical and developmental studies were undertaken of a new "double" type of proteinaceous globules in fat body and haemolymph of Aphodius constans Duft. The homogeneous globules first appear in the late first instar or the early second instar larva—i.e. earlier than in other insects. In the middle of the third instar the central region of the globules begins to differentiate into a core, much resembling the polyhedron of a nuclear insect virus. The cores are, however, not a pathological phenomenon, but constitute normal reserve substances, present in all individuals, especially in the prepupa, the pupa and the early adult. Both the core and the periphery of the "double" globules, as well as "empty" globules from second and third instar larvae, contain proteins and ribonucleic acid, although the cytochemical reactions of the core was always the most intense. Neither lipids, carbohydrates, desoxyribonucleic acids nor uric acid are deposited inside the globules. There is no membrane around the globules.