Descriptions of structures of the second and third instars of Heterosternuta sulphuria (Matta and Wolfe) are presented. Larvae of H. sulphuria are fairly similar to the known larvae of Heterosternuta Strand, all of these being characterized by the presence of lateral spinulae on the prementum, the absence of natatory setae on the legs, the absence of spiracular openings on the mesothorax and abdominal segments 1–7, siphon of the third instar cone-shaped, short, and highly constricted posterior to insertion of urogomphi, and urogomphomere 1 with secondary setae. A key to identification of the third instars of known species of Heterosternuta is provided.