Colonization and abundance of mosquitoes and other insects were studied during four trials in man-made ponds at Mildura, Victoria. In December and February, respectively, Culex australicus and Cx annulirostris colonized the ponds within 1 day of formation. Maximum larval densities were attained within 8 days and, thereafter, densities gradually declined. The ponds were also colonized initially by predatory Coleoptera and Hemiptera, then Odonata. In three of the four trials, a significant inverse relationship existed between mosquito and predator densities. From life tables compiled during one of these trials, a survival rate of Cx annulirostris, from egg hatch to eclosion, was estimated to be 11%. Predation was considered to be largely responsible for the low survival. The results are discussed in relation to control of Cx annulirostris in temporary and permanent grassy ponds.