Larva and pupa of the Patagonian species Culicoides lacustris Ronderos are described in detail with phase-contrast microscope at oil immersion and scanning electron microscope. Studied specimens were collected in a wetland, alongside to the Provincial Route 12, between the cities of Esquel and Gualjaina in the Chubut Province. They are compared with the more similar congener, Culicoides venezuelensis Ortiz & Mirsa.

Adult males and pupae of Culicoides guarani Ronderos & Spinelli and Parabezzia brasiliensis Spinelli & Grogan are fully described and illustrated with a modern criterium from material recently collected in the vicinities of the city of Posadas in Misiones province, Argentina. Both species are compared with their most similar congeners. Besides, Bezzia blantoni Spinelli & Wirth and B. brevicornis (Kieffer) are firstly recorded from Misiones province.

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The fourth instar larva of Dasyhelea mediomunda Minaya is described for the first time and a complete description of the pupa is provided, through use of phase-contrast microscope and scanning electron microscope. Studied specimens were collected in a pond connected to a small wetland "mallin" on the Patagonian steppe, Chubut province, Argentina.