What They Look Like
Mosquitoes are small, slender flies that are members of the family Culicidae. When viewed under a hand lens, adult mosquitoes are easily recognizable--scales cover the wing veins and the hind wing margin. The scale and setal (bristle) patterns of the adults are distinctive characteristics for species identification. Mostly you see that hypodermic needle they carry for a nose. There are at least 100 known species of mosquitoes in the United States and Canada.
Like butterflies, mosquitoes undergo complete metamorphosis and have egg, larval, pupal, and adult stages. Of the blood-sucking mosquito species, a blood meal is usually (but not always) necessary for egg maturation. The eggs may be laid singly or in rafts but always in association with water and where it is quiet and protected. Females may lay up to 100 eggs per batch and deposit an egg batch every 7 or 10 days. Eggs can take from days to months to hatch. In general, during warm periods and under favorable conditions, eggs will hatch in a few days. However, the eggs of "flood-water" mosquitoes can remain dormant and are capable of surviving for months out of water until they are flooded. Eggs may be laid at the water surface, at the water-soil interface along banks, or on soil or vegetation that is subject to periodic flooding, depending on the species involved. Other sites where eggs may be deposited include tree holes, temporary puddles, freshwater and salt marshes, and containers in which water stands, such as discarded tires, cans, pet water dishes, and bird baths.
The larvae have no legs and have an enlarged thorax that is much wider than the head and abdomen. Larvae prefer quiet, still water, and are commonly referred to as "wrigglers," which describes their movement in water. They feed on decaying organic matter that includes microorganisms. After hatching, the larva goes through four molts, with the final molt resulting in a pupa. The larval stage typically is completed in about 7 to 10 days.
The pupa is a mobile but nonfeeding stage. The pupae are frequently called "tumblers" because when they are disturbed at the water surface, they will quickly tumble downward and then rise slowly rise to the water surface. After 2 or 3 days, the pupa molts into the winged adult.
The longevity of the adult varies greatly. During the heat of summer, most adult females do not live more than 2 weeks. The males have a shorter life span.
Although many species of mosquitoes have a wide geographic distribution in the United States, their local abundance varies greatly. Warmth, precipitation, and favorable microhabitats influence potential population levels of the immature stages. Eggs laid in flood-prone sites can accumulate for years until they hatch under favorable environmental conditions, thus resulting in explosive population levels within a relatively short period of time.