In order to manage mosquitoes that can carry and transmit diseases it is crucial to understand the ecology of mosquitoes and identify the habitats in which they breed.
Mosquitoes lay their eggs, singly or in rafts, on or near standing water or along the margins of rivers that are subject to periodic flooding. Under suitable environmental conditions, the eggs hatch within a few hours into tiny larvae, which feed on microscopic organic suspended materials. The larvae are air breathers and thus typically remain just below the surface with the specialised body part called the spiracle open to the air to breathe. When disturbed, the larvae usually wriggle down into the sediments.
The larvae undergo four different stages of development (instars) within an average of ten days, depending on the water temperature and availability of resources. The final stage is usually the longest, lasting several days, after which pupation occurs. The 'comma-shaped' pupa swims efficiently just under the water surface and breathes air but is no longer able to feed. After several days, the adult mosquito then emerges from the pupal case and rests above water for a short time until blood is pumped into the wings. Mating usually follows soon after the first flight and most females then immediately search for a blood meal. After ingestion of sufficient protein, the eggs develop in the female and she searches for a suitable egg-laying site. Female mosquitoes have a life span of anywhere from a couple of weeks to several months, and some species can overwinter.
Birds, amphibians and dragonflies may predate the adults during the day, and at night many mosquitoes fall prey to bats. Many mosquito species fulfill the larval stage of their life cycle in a relatively predator-free environment by using temporary pools that predators do not use. In contrast, deep, permanent waterbodies are poor larval habitat because they tend to have resident predator populations.