The third instars of Hylamorpha elegans (Burmeister, 1844) and Aulacopalpus punctatus (Fairmaire and Germain, 1860) (Scarabaeidae: Rutelinae: Anoplognathini) are described. Descriptions are based on larvae reared from eggs laid by adults in the laboratory and larvae collected in the field. These are the first descriptions of anoplognathine larvae from southern South America. The larvae feed in the root layer in pastures. The two species are easily distinguished by the coloration and roughness of the cephalic capsule and the distribution and shape of the setae on the raster.