Nymphal instars of Xyleus discoideus discoideus, a romaleid grasshopper, are described for the first time. The following characters are recorded for each stage: body length, head width, pronotal length, hind femoral length, number of antennomeres, number of longitudinal eye stripes and the morphology of wing pads and external genitalia. Criteria that can be used to distinguish the instars and sexes are identified. Males and females have a 5-instar cycle under laboratory conditions. Females are larger as adults than males and this is linked to a longer nymphal period in females.