Résumé
Larvae (white grubs) of many scarab beetle species can be found in rainfed rice fields in medium and high altitude areas of Madagascar, with certain species being pests. For pest management, it is therefore critical to be able to accurately identify them. Raster morphology makes it possible to determine the difference between species. Twenty six larvae morpho-species were thus distinguished, of which 18 species, whose larvae and pupae were unknown, were identified after development to adults: Bricoptis, Celidota, Anochilia, Euryomia (Cetoniidae, four species), Heteronychus, Hexodon, Heteroconus, Paranodon (Dynastidae, seven species), Paramorphochelus (Hopliidae, one species), Encya, Enaria, Apicencya, Empecta, Hoplochelus (Melolonthidae, five species) and Triodontus (Orphnidae, one species). Original descriptions of third instar larvae of 17 species, and of pupae of 13 of them are given, along with an identification key of 25 larvae morpho-species. Pupae external genitoanal structures concept is defined. All diagnostic traits are illustrated.