The ontogeny of agonistic displays associated with territory maintenance by Xanthocnemis zealandica larvae is described. Display repertoire and patterns of display use shift as larvae develop from second-instar to final- (=c. 14th) instar. Displays and frequency of display use change, consistent with the developing sensory capability of the growing larvae. Repertoire size does not change markedly during development but there is almost complete turnover in the set of most frequently used displays. The opportunity is taken to correct descriptions of some behaviours observed in small larvae.