Postemergence Growth in the Fly <Emphasis Type="Italic">Sarcophaga falculata</Emphasis> initiated by Neurosecretion from the Ocellar Nerve

THE formation of the endocuticle and growth of skeletal muscles which takes place in the fly after eclosion is termed the postemergence growth. An increase in volume of skeletal muscles was observed in Glossina¹ and the deposition of cuticular growth layers described for some orders of both Exopterygota² and Endopterygota³. The postemergence growth which was shown to be induced by some blood-borne factor from the head⁴, hitherto considered to be the tanning hormone bursicon⁵, is initiated by neurosecretion from the ocellar nerve of the pharate adult. Experiments have been performed which indicate that neurosecretion induces the growth of the endocuticle. The process of postemergence growth was assessed by measuring the size of the longitudinal skeletal apodemes. This begins after eclosion and is correlated with the growth in thickness of the cuticle. The enlargement of the surface of the apodemes also indicates the growth of the skeletal muscles, which spread over the newly deposited cuticle. This phenomenon is a constant feature of this species since more than 2,000 specimens were examined at different periods of the year and none were found in which postemergence growth had not occurred.