The Circadian Clocks of Insect Eclosion

Understanding the circadian timing of eclosion in insects is a pretty big undertaking. A lot of technical detail is essential and a lot of close reasoning from meticulous experiments stands in the place of direct observations on the “clock’s” unknown physiological mechanism. In that respect clockology has some of the intellectual delight of the earlier years of genetics. However, the whole argument has never been spelled out for publication in one place. This chapter once again attempts only an outline of the essentials. The story presented here seems to be generally valid for butterflies and moths, flies and mosquitos, wasps and bees (i.e., Lepidoptera, Diptera, and Hymenoptera), but I emphasize my own experimental beast, the fruitfly. For a review of insect eclosion systems from the viewpoint of physiology and ecology, see Remmert (1962).