Silk moth eclosion: hormonal triggering of a centrally programmed pattern of behavior.

The emergence of the adult cecropia silk moth from the pupal skin involves a stereotyped series of abdominal movements-the pre-eclosion behavior. This behavior, triggered by a neurosecretory hormone, consists of three phases that are characterized by the relative frequency and pattern of movements. Electrical recordings from a nerve cord with severed peripheral nerves demonstrate that the pre-eclosion behavior is prepatterned in the abdominal ganglia. In response to the hormone, the entire 1.25-hour behavioral program can be activated and "read off" in the absence of sensory feedback.