This monograph represents the current status of neuro­ ethological research on the diurnal behavior of the stick in­ sect, Carausius morosus. The growing profusion of inter­ related studies, many of which are published only in German, makes an overview of this field increasingly difficult. Many stick insect results contribute to general problems like control of catalepsy, control of walking, program-dependent reactions and control of joint position. For this reason I decided to compile and synthesize the results that are pre­ sently available even though the analyses are far from con­ cluded. In addition to both published and unpublished results of the group in Kaiserslautern (Bassler, Cruse, Ebner, Graham, Pfluger, Storrer, as well as doctoral and masters students), I have drawn upon the literature which had ap­ peared as of summer 1981. This includes above all the work of Godden and of Wendler and his colleagues in Cologne. A summary of the anatomical and physiological background, necessary for an understanding of these investigations, is provided in an appendix (Chap. 6). Methodological details must be obtained from the original publications. Figures for which no source is given are from my own studies. I intend to update this monograph on an annual basis. Requests for these supplements should be directed to me in Kaiserslautern. I would like to express my appreciation to all members of the group in Kaiserslautern for their constructive discussions, their unflagging cooperation, and their permission to include hitherto unpublished results.