There are over 3,000 species of mosquitoes in the world. The most common, and most dangerous, are the various species in the Culex, Anopheles, and Aedes genera.
These mosquitoes tend to hibernate over the winter and breed during the warmer months, laying rafts of eggs at night on the surface of standing water anywhere it can be found. Over a period of about two weeks, the eggs hatch, larvae emerge, develop into pupae, and then into adult mosquitoes.
They normally don't travel more than a few hundred yards from where they hatched. Adults feed primarily from dusk until a few hours after dark and are considered aggressive and persistent biters, although they prefer birds to people. Females need the protein in blood to develop eggs, which they lay about every third night. They can live up to a month.
Mosquito species in this group also breed during the warmer months. Females also deposit their eggs on the surface of water in groups of 50 to 200. The eggs hatch and go through the same developmental process as Culex mosquitoes. However, unlike other mosquito larvae, Anopheles larvae do not have breathing tubes, so they must lie parallel to the surface and breath through holes in their sides called spiracles.
While Culex mosquitoes can breed and thrive in stagnant or polluted water, the Anopheles mosquitoes prefer clean water habitats in marshes, swamps, and rice fields, among others. The adult females usually live about two weeks and feed at dusk and dawn. They tend to feed on people and cattle, rather than other warm-blooded creatures.
Anopheles mosquitoes are the carriers of the parasite that causes malaria and transmit the bugs through their saliva when they bite. More than one million deaths each year are attributed to malaria passed on by Anopheles mosquitoes.
The mosquitoes in this genera are floodwater mosquitoes, meaning they lay their eggs on moist soil or in containers that periodically catch rainfall.
They prefer to breed in treeholes, overflow ditches, and old tires. The eggs can survive drying and hatch once flooded by water. They develop in a four-stage process like other mosquitoes. As a predominantly tropical and subtropical group, Aedes mosquitoes tend to breed in warm weather, although some species can survive in colder environments. The adults feed day and night, and several of the species are considered particularly troublesome.
Aedes vexans, the inland floodwater mosquito, is known as a fierce and painful biter. Two Aedes mosquitoes are also carriers of dangerous disease. Aedes albopictus, the Asian tiger mosquito, transmits dengue fever and eastern equine encephalitis, while Aedes aegypti, the yellow fever mosquito, transmits dengue and yellow fever.
An indication of the general of mosquito larvae can be made from the length of the siphon. Anopheles have very short siphons, while Culex tend to have the longest siphons. Mosquito larvae, commonly called "wigglers" or "wrigglers", must live in water from 7 to 14 days depending on water temperature.
Larvae must come to the surface at frequent intervals to obtain oxygen through a breathing tube called a siphon. The larva eats algae and small organisms which live in the water. During growth, the larva molts (sheds its skin) four times. The stages between molts are called instars.
At the 4th instar, the larva reaches a length of almost 1/2 inch. When the 4th instar larva molts it becomes a pupa. Note : Anopheles are unlike Culex and Aedes larvae since they do not have a breathing tube, they must lie parallel to the water surface in order to get a supply of oxygen through a breathing opening.