Mosquito control starts in the swamps, marshes, seepage ponds, and any other area that holds shallow stagnant water. To understand why water is critical to mosquitoes, one must understand the mosquito life cycle. Mosquitoes have four distinct stages in their life cycle: egg, larva, pupa, and adult.
Depending on the species of mosquito, eggs are laid either singly or attached to each other in groups of 50-200 eggs. When the eggs are joined, they are called an egg raft. Most mosquitoes lay their eggs directly on the water surface where they hatch into larvae a couple of days later. There are also some mosquitoes which lay their eggs on the ground next to the water. When the water rises from increased irrigation, snow melt, etc., the eggs hatch and the larvae emerge. Regardless of the mosquito species, all larvae require water to survive.
Once the larvae emerge from the egg they begin filter feeding. At this point in their life cycle they feed only on microorganisms and small organic material in the water. The larvae breathe through a siphon tube that penetrates the water surface. During their larval stage, the mosquitoes will shed their skin and molt four times before changing to the pupal stage of their life cycle.
The pupal stage is where metamorphosis occurs, creating the adult mosquito. During the pupal stage they are no longer feeding as they have ingested enough nutrients to make the transition into an adult. This phase of the life cycle is similar to the cocoon of a butterfly although the mosquito pupa is fully active and mobile. Alike the larval stage, the pupal stage of a mosquito is entirely aquatic, and the mosquito will perish if it is removed from the water.