The larva of Aeshna williamsoniana Calvert, 1905 is described in detail, illustrated, and compared with other larvae of the genus and family. It is distinguished from its congeners by its granular integument, body mostly lacking hairlike setae, cerci with a row of spiniform setae along the lateroexternal margins, and dorsomedial margin of female epiproct with a row of spiniform setae. It does not particularly resemble any other larva of Aeshna or related genera described to date. The larval habitat is described for the first time.