The four larval instars of Sabethes chloropterus are illustrated and the salient features of each are described and discussed in relation to species of other genera. Eight specific criteria for determining setal homologies are stated and used to establish homologies for the ventral abdominal setae of first instar larvae. The facts of development of setae 7-P, 8-M, 7-T, 9,12-I-VII, and 4-X are reviewed and discussed in terms of heterochrony. Setae retain their relative positions during development, and the importance of this phenomenon in recognizing phylogenetic relationships is noted.