Introduction to Mosquito
Mosquito, the most dangerous insect pest to man. Most species of mosquitoes are harmless. However, several species carry and transmit diseases. Mosquitoes are the only agents that carry and transmit malaria, yellow fever, dengue fever, and filariasis to man. They are leading agents in transmitting several forms of viral encephalitis. Mosquitoes also transmit certain diseases to animals.
Mosquitoes inhabit nearly all parts of the world except deserts. They have been found at altitudes of 14,000 feet (4,300 m), and some species live within the Arctic Circle. They have made some areas uninhabitable by man.
There are more than 3,000 known species of mosquitoes, divided into about 100 large groups, or genera (singular: genus). Among the best-known groups in North America are the Culex, the Aedes, and the Anopheles. In the United States, two species of Anopheles transmit malaria. Two species of Aedes and two species of Culex transmit viral encephalitis.
Facts in brief about mosquitoesNumber of eggs: 50 to 200 at a time, depending on species. As many as 1,000 a year for each female.Length of life: 30 days or more for females; about 7 to 10 days for males.Where found: All parts of the world.Scientific classification: Mosquitoes make up the mosquito family, Culicidae. The scientific name of the common house mosquito is Culex pipiens. The yellow fever mosquito is Aedes aegypti, and the Asian tiger mosquito is A. albopictus.Description
Mosquitoes are true flies, having only one pair of wings. (Their name comes from the Spanish for “little fly.”) The mosquito, unlike other true flies, has scales along the wing veins and on other parts of its body, and has 14 or 15 segments to each of its two antennae.
The average mosquito is about one-fifth of an inch (5 mm) long, with a slightly shorter spread of its narrow wings. Its body, like that of other insects, consists of head, thorax, and abdomen. The round head has a long proboscis (tubular mouth part) and antennae. In the male, long hairs on the antennae give these appendages a feathery appearance. Hairs on the antennae of the female are shorter. The mosquito's slender legs are attached to the triangular thorax. The abdomen is long and narrow.
Habits
Some species of mosquitoes are active during the day and rest at night. Most species of Culex and Anopheles are active at night and rest by day. Culex rests with its body parallel to the supporting surface. Anopheles rests with the head down, and the body at an angle to the support. The high-pitched buzzing sound associated with mosquitoes is made only by the females—by vibrating the tiny appendages that cover the spiracles (breathing holes) in the thorax.
Life Cycle. Mosquitoes lay their eggs in water, or where water will eventually cover the eggs. In arctic regions, eggs are laid in snow, and hatch when the snow melts. The eggs of some species are laid singly. Other mosquitoes, including Culex, lay eggs in flat groups of 100 to 300 that float on the surface of water.
The eggs hatch as larvae, usually in a few days. The larvae are commonly called “wrigglers” or “wigglers” because of the way they move in seeking food and in rising to the surface to breathe. After a few more days, the larvae develop into pupae. Each pupa has an extremely large head and thorax. Its way of moving has gained it the popular name of “tumbler.” Pupae do not eat. When the pupa is full grown, usually in two or three days, it rises to the surface and splits its skin from end to end and sheds it. The insect stands balanced on its shed skin until its wings dry, and then it flies away. It takes about 10 days for the egg to develop into a mature adult mosquito.
Feeding. The male mosquito is harmless. It uses its proboscis for sucking only, and feeds on plant juices and pollen. It helps pollinate several species of flowers. The proboscis of the female is adapted for piercing as well as sucking, and can penetrate the skin of reptiles, birds, and mammals, including humans. Females require a certain protein found in the blood of these animals to nourish their eggs before they are laid. The proboscis contains saw-tipped cutters and two tubes. One of the tubes is used to inject saliva after the cutters have pierced the skin, and the other is used to suck up blood. The saliva thins the blood and makes it easier for the mosquito to suck.
Mosquitoes and Disease
Bacteria and viruses enter the mosquito's body and multiply there before they are transferred to other animals by the mosquito's bite. The protozoan that causes malaria must go through part of its life cycle in a mosquito before it can infect humans.
Eliminating marshes, swamps, and other breeding places has helped control mosquito populations. Eliminating marshes and swamps is often undesirable, however, because many are valued as wildlife habitats. Another control measure is spraying a larvicide on water surfaces where eggs are laid. Adult mosquitoes are killed with such insecticides as malathion. Some drug-resistant strains of mosquitoes have developed, and researchers constantly seek new insecticides. Screens on doors and windows, and mosquito netting over beds, provide protection from these insect pests. Repellents containing a chemical substance called DEET (diethylmeta-toluamide) are effective when applied to the skin and clothing.
Mosquitoes belong to the family Culicidae of the order Diptera. The most common house mosquito in the United States is Aedes vexans; in the tropics, Culex pipiens. The three species of mosquitoes that transmit encephalitis in the United States are Aedes triseriatus, Culex nigripalpus, and C. quinque-fasciatus. The two species of mosquitoes that carry malaria in the United States are Anopheles freeborni and A. quadrimaculatus.