Lifecycle

lifecycle-diagramThere are 3 main habitats for insects terrestrial, semi-aquatic and aquatic. Mosquitoes spend part of their lifecycle in the water so they are semi-aquatic insects. All mosquitoes have four stages of development - egg, larva, pupa and adult. Eggs can be laid directly onto the water or in areas that will be flooded with water. Larval and pupal stages are spent in water and the adult stage is spent out of water. Each of these stages can be easily recognized by its special appearance.

The egg, larval, and pupal stages, female ovarian development, and adult life span all depend on temperature, food supply, and species characteristics. Optimum temperature range for mosquito development is 75 - 85 degrees Fahrenheit. Under this range, eggs take 2 days to hatch, larvae take 5-7 days to become pupae, pupae take 2 days to emerge. Male adults survive for 2-3 weeks. Female adults take 3-4 days to develop eggs after a blood meal and survive for 4-5 weeks. They may suck blood and lay eggs 2-3 times. An entire life cycle takes about 10-14 days.

 

Eggs are laid by gravid females, one at a time or attached together to form "rafts" on the surface of the water. The female of some mosquito species deposit eggs on moist surfaces, such as mud or fallen leaves, that hold water but dry. Later, rain or high tides re-flood these surfaces and stimulate the eggs to hatch into larvae, for example, the salt marsh mosquitoes. The females of other species deposit their eggs directly on the surface of still water in such places as catch basins, tire tracks, ditches, streams, and pools, for example, Anopheles and Culex mosquitoes.

 

egg

The larvae live in the water and come to the surface to breathe. Larvae molt their skins four times, growing larger after each molt. Based on the molt time and size, larvae are divided into 4 stages or instars (from 1st instar to 4th instar). Larvae of Culex, Aedes, and Ochlerotatus mosquitoes have siphon tubes for breathing and hang upside down from the water surface. Anopheles larvae do not have a siphon (air tube) and lie parallel to the water surface to get oxygen supply through a spiracular opening. Some species, such as Coquillettidia and Mansonia larvae attach to plants to obtain their air supply. The larvae feed on microorganisms and organic matter in the water.

 

larva

Pupae are mobile, responding to light changes and move with a flip of their tails towards the bottom or protective areas. A pupa is a resting, non-feeding development stage. This is the time the pupa changes into an adult. When development is complete (usually 2 days), the pupal skin splits and the adult mosquito emerges.

 

pupa

The newly emerged adult mosquitoes include male and female, usually, 1:1 rate of male and female mosquitoes. The new adults rest on the surface of water for a couple of hours to dry and harden its exoskeleton (hard, outer protective shell). The wings spread and dry before it can fly. They fly to nearby vegetation and plants to rest and /or suck plant juice / nectar. After a couple of days, males and females begin to mate and after females are mated they will take a blood meal from animals and humans for their egg development. However, some species can develop their eggs without a blood meal. After a blood meal (3-4 days), gravid females start to lay eggs. adult
Source: Health Canada's West Nile virus Web site, Health Canada, http://www.westnilevirus.gc.ca. © Her Majesty the Queen in Right of Canada, represented by the Minister of Health (2003)

Click here to see an organizational chart of the life cycle as well as an extremely informative video. 

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