Abstract A brief account is given of the anatomy of the stomatogastric nervous system. The role of this system with regard to the postembryonic growth of the locust was investigated by cutting certain of the nerves, removing certain of the ganglia, and observing the effect of these operations on the further growth and moulting of the locust. An account of the technique of each operation is given, and stress is laid on certain asceptic procedures which were found to greatly decrease the mortality rate of the operated animals. All operations were performed on 33-hr-old third instar locusts. Cutting the ventral nerve cord in front of the first abdominal ganglion had little effect on the further growth and moulting of the insects which survived into the adult instar. Cutting the outer oesophageal nerves did not prevent the animals moulting and growing to the fifth instar; however, the growth was slower and the mortality higher than in the operated controls. Removal of the ingluvial ganglion resulted in death within 43 hr of the operation. Cutting the recurrent nerve behind the frontal ganglion did not prevent the animals from moulting and growing to the end of the fourth instar; growth was slower than that of the operated controls. Removal of the frontal ganglion resulted in the immediate cessation of growth, the animal remaining at a constant weight and without moulting until its death. Death occurred at between 260–310 hr which is approximately twice as long as it took the operated control to grow and moult to the next instar. The operated animals were observed to feed frequently, to defecate normally, and upon dissection their guts were found to be full of fresh food. These effects cannot therefore be attributed to a failure to feed. These experiments show that the frontal ganglion has an essential role in the growth of the locust which, however, can survive and show normal activity in its absence.