Abstract The first description of the fourth instar larva and pupa of Palpomyia mapuche Spinelli, Grogan & Ronderos and the pupa of P. subfuscula Ingram & Macfie are provided, as well as the redescription of the pupa of P. subaspera (Coquillett). Studied specimens were collected in lotic environments of Argentinian Patagonia, in Neuquén and Chubut Provinces. The described stages were examined and illustrated with a phase-contrast microscope. The larva was examined using a scanning electron microscope. Data on the bionomics for P. mapuche and new records for the three species are provided.

RESUMO A larva de quarto ínstar de Dasyhelea mediomunda Minaya é descrita pela primeira vez e a descrição completa da pupa é fornecida, através da utilização de microscópio de contraste de fases e microscopia eletrônica de varredura. Os espécimes estudados foram coletados em um "mallin" conectado à zonas úmidas na estepa patagônia, Província de Chubut, Argentina.

ABSTRACT 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.