Control of melanization in first instar larvae of Schistocerca gregaria

Melanization in first-instar larvae of Schistocerca is controlled by a hormone released from neurosecretory axon terminals of the fine nerves posterior to the metathoracic ganglion. The hormone is not detectable in the haemolymph before the embryonic ecdysis but is present within seconds after the ecdysis has started. It is suggested that horizontal displacement of the embryonic cuticle is the trigger for the release of the hormone and that the prothoracic ganglion forms part of the neural pathway between the sensory input caused by ecdysis and the release of the hormone.