Mosquito eggs were hatched by artificially flooding dry pond beds and estimates of population size were made through larval development for one population of Aedes spencerii, two of A. cataphylla, and three of A. vexans. Overall daily mortality rates were between 8 and 21% and survival to the pupal stage was generally less than 20%, even though water levels were maintained. Mortality appeared to be higher in early larval stages than in later larval stages. Predation was unimportant and survival rate may have depended on food supply or temperature or an interaction between the two. In normal ponds populations often suffer heavy mortality when ponds dry up before development is complete. A. cataphylla, a spring species, developed faster than A. vexans, a summer species, at low temperatures but more slowly at high temperatures.