Tenebrionid beetles are probably the best studied insect group of the Namib Desert. Most of the studies have concerned themselves mainly with taxonomy and, more recently physiology, behaviour and ecology. No investigation known to date has endeavoured to establish if reproductive cycles exist, or to evaluate the factors controlling time of reproduction of desert tenebrionids in their natural habitat. Keywords: Namibia, Namib Desert, Kuiseb River, Tenebrionidae, Onymacris plana, Onymacris rugatipennis, Onymacris laeviceps, desert beetles, reproductive cycles, reproductive behaviour, food abundance, arid ecosystem, arid environment.