The discovery of insect neurohormones dates from the earliest experimental in vestigations in insect endocrines, and the matter cannot be discussed without evoking the names of its pioneers-Kopec, Wigglesworth, Fraenkel. Whereas the experiments demonstrated the existence of the first known neurohormones, the formulation of the concept of neurosecretion was of fundamental importance to further progress, and tribute must be paid to Ernst and Berta Scharrer. The recent proliferation of investigations into insect neurohormones has cre ated the need for an overall review of the data. Our knowledge...