The ultrastructure and development of new stylets was studied in pre-molting first instar nymph of Diaphorina citri Kuwayama (Hemiptera: Liviidae). Two oval-shaped masses of cuboidal hypodermal cells, located in the cephalic region, had long extensions that ended with developing pairs of mandibular and maxillary stylets, apparently coiled around these masses. A new structure, probably composed of softer cuticle, was found on the ventral side of each developing stylet suggesting that this structure may work as a mold during formation of the new stylets. Other organs of 1st instar nymphs, including the filter chamber and bacteriome, are also ultrastructurally described.