Many mosquitoes exploit newly wetted and/or ephemeral habitats that are prone to dry up. This is likely due to the lack of competition from other organisms with which they compete for nutrients. Alternatively, ephemeral habitats offer a lower risk of predation from natural enemies that may have not had time to invade these habitats. In nutrient-rich habitats, such as those influenced by sewage discharges, competitive effects presumably are not as important as predatory effects. Instead, immature mosquitoes race to complete their aquatic development (egg—larvae—pupae) before they are eaten by aquatic predators—most notably the mosquitofish.