Third instar larva and pupa of Cnemida leprieuri Arrow, 1899 and third instar larva of Cnemida retusa (Fabricius, 1801) (Coleoptera, Scarabaeidae, Rutelinae) are described and illustrated based on specimens collected within rotten logs in North Brazil. The pupation of C. retusa is discussed. Third instar larvae of both species are compared with the only formerly known larva to the genus: Cnemida intermedia Bates, 1888. Formerly disponible generic keys to the third instar larvae and to pupae of New World Rutelini are updated. A key and a comparative study of chaetotaxy to known third instar larvae of Cnemida are also provided.