Faced with "appropriate" food at the "right" time, most insects will feed to a point and then stop. What causes an insect to begin feeding? What finally causes it to stop? Such questions have received their most detailed investigation in the cause of the blow fly, Phormia regina, primarily through the work or Dethier (1962, 1976) and his associates. Of all the animals, the only one that rivals the blow fly when it comes to understanding the mechanisms regulating feeding is the laboratory rat. Even then, the insect system is better understood.