Aedes caspius in the south western part of Morocco : impact of the aridity to preimaginal populations dynamic (Diptera, Culicidae). A regular study of the spatio temporel dynamic of Aedes caspius aquatic larvae in temporary pools in Marrakech area (south part of Morocco) shows that their reduced space, the water level dynamics and the physicochimical factors variations activate hatching eggs and accelerate the larvae développement. However, the number of generations is depending on the water level dynamics which is influenced also by the arid climate.