Mosquitoes are common flying insects in the family Culicidae that are found around the world. There are about 3,500 species. They have a pair of scaled wings, a pair of halteres, a slender body, and six long legs. The females of most mosquito species suck blood (hematophagy) from other animals, which has made them the deadliest disease vector known, killing millions of people over thousands of years and continuing to kill millions per year by the spread of infectious diseases.

Development

Mosquitoes go through four stages in their life cycle: egg, larva, pupa, and adult or imago. The first three stages are aquatic and last 5–14 days, depending on the species and the ambient temperature. The adult females can live up to a month (or more in captivity) but most probably do not live more than 1–2 weeks in nature.

Egg

After drinking blood, adult females can lay a raft of 50-300 eggs per oviposition. Anopheles, Ochlerotatus and Aedes, as well as many other genera, do not make egg rafts but lay eggs singly. Culex, Culiseta, and Anopheles lay eggs directly on the water surface and Anopheles are unique in having floats on either side. Eggs are not resistant to drying and hatch within 2–3 days, although hatching may take up to 2–3 weeks in colder climates. In other mosquitos such as Aedes, the female lays her eggs on damp soil that will be flooded by water, typically near a stagnant pool. However, any open container containing water will suffice for larvae development, even with less than an ounce of water in. Aedes can also breed in running water, so stagnant pools of water are not its only breeding sites. With Haemagogus as the adults tend to live in the canopy of forests, the female lays eggs in between layers of tree bark or in cut bamboo. The eggs adhere to the surface and when submerged by rain water quickly develop into larva.

Larvae

Larvae breathe through spiracles located on the 8th abdominal segment and therefore must come to the surface frequently. The larvae spend most of their time feeding on algae, bacteria, and other microorganisms in the surface microlayer. They dive below the surface only when disturbed. Larvae swim either by jerky movements of the entire body or through propulsion with the mouth brushes. Larvae also like very warm temperatures.

Larvae develop through 4 stages, or instars, after which they metamorphose into pupae. At the end of each instar, the larvae molt, shedding their exoskeleton, or skin, to allow for further growth.

Pupa

The pupa is comma-shaped in Anopheles when viewed from the side. The head and thorax are merged into a cephalothorax with the abdomen curving around underneath. As with the larvae, pupae must come to the surface frequently to breathe, which they do through a pair of respiratory trumpets on the cephalothorax. After a few days as a pupa, the dorsal surface of the cephalothorax splits and the adult mosquito emerges.