A STUDY OF LARVAL MORPHOLOGY OF ARGIA MOESTA (HAGEN) (ZYGOPTERA: COENAGRIONIDAE). A. moesta larvae reared under laboratory conditions show four different growing types, characterized by 12, 13, 14 and 15 instars respectively. This paper is concerned with the morphology of larval forms for individuals of the 14-instar type. Also included is a comparative study of the variability of major morphological structures (antenna, labium, tarsal segmentation, pedal combs, wing pads, gonapophyses and caudal lamellae).