Mosquitoes and its Life Cycle

Mosquitoes and its Life Cycle

What is Mosquitoes and its Life Cycle?

• Mosquitoes belong to the group of insects known as diptera, or flies.
• In fact, mosquito means “little fly” in Spanish.
• Diptera means “two wings” – the characteristic that distinguishes flies from other types of insects.
• What distinguishes a mosquito from other types of flies are its proboscis and the hair-like scales on its body.
• The female mosquito’s life is often measured in weeks or months.
• Males typically live only about a week.
• Mosquitoes hatch from eggs laid in places that are or will be filled with water.
• The eggs hatch into worm-like larvae that usually lie just beneath the water’s surface, breathe through tubes on the tail end of their bodies, and feed on microscopic organisms, such as bacteria.
• Thus most mosquito larvae require water containing organic material, such as leaves or sewage to serve as food for microorganisms that will be consumed by the developing mosquito larvae.
• In less than a week, hatchling larvae can grow and develop into comma-shaped pupae.
• While larvae are commonly called “wigglers” because they wiggle violently when disturbed, mosquito pupae are known as “tumblers”  because they tumble through the water when disturbed.
• While mosquito larvae and pupae breathe through siphon-like devices, the pupal stage does not feed.
• Usually within three days the pupa will transform into an adult mosquito.
• There are some notable exceptions to the standard mosquito life cycle.
• The larvae of some mosquito species eat the larvae of other species, though the predatory larvae of some species will develop into blood-feeding adults.
• Female mosquitoes can be particular about whose blood they consume, with each species having its own preferences.
• Most mosquitoes attack birds and mammals, though some feed on the blood of reptiles and amphibians.
• Only female mosquitoes bite, because a blood meal is usually required for egg laying.
• All male mosquitoes, and the females of a few species, do not bite. They feed on nectar and other plant juices instead of blood.
• Mosquitoes can fly long distances; some more than 20 miles from the water source that produced them.
• But they don’t fly fast, only about 4 miles an hour.
• And because they typically fly into the wind to help detect host odors, fewer mosquitoes are about on windy days.
• As a mosquito flies closer to its target, it looks for the movement of dark objects. Once it finds you, it lands, inserts its proboscis and probes for blood vessels beneath the skin.
• When it finds one, it injects saliva into the wound.
• The saliva contains an anticoagulant that ensures a steady, smooth flow of blood. Unfortunately, the mosquito’s saliva also may contain pathogens such as malaria parasites or encephalitis virus.

CULEX MOSQUITOES

• The West Nile virus is transmitted predominantly by Culex mosquitoes.
• Culex are medium-sized mosquitoes that are brown with whitish markings on the abdomen.
• These include the house mosquitoes that develop in urban areas, and the western encephalitis mosquito more commonly found in rural areas.
• They typically bite at dusk and after dark. By day they rest in and around structures and vegetation.
• Culex lay “rafts” of eggs on still water in a variety of natural and man-made containers, including tree holes, ditches, sewage and septic system water, catch basins (storm drains), non-chlorinated swimming and wading pools, decorative ponds, bird baths, flower pots, buckets, clogged gutters, abandoned tires, and water-retaining junk and debris of all sorts.
• They cannot develop in running water and water that is present less than a week. Therefore, every effort should be made to prevent water from accumulating in containers or, at least, empty water out of them on a weekly basis.
• Adult Culex mosquitoes do not fly far from where they develop as larvae.
• And unlike other mosquitoes that die with the coming of the first hard frost in autumn, the house mosquito can “over-winter” in protected places like sewers, crawlspaces and basements.

AEDES MOSQUITOES

• The Aedes group of mosquitoes includes many nuisance mosquitoes, as well as species that transmit disease to humans.
• This is a diverse group that includes the inland floodwater mosquito (Aedes vexans), the Asian tiger mosquito (Aedes albopictus) and the tree hole mosquito (Ochlerotatus triseriatus*) – all of which prefer to feed on the blood of mammals.
• Floodwater mosquitoes lay their eggs on soil that becomes flooded, allowing the eggs to hatch and larvae to develop in temporary pools.
•  Asian tiger and tree hole mosquitoes are container-breeding mosquitoes, laying their eggs in small, water-filled cavities, including tree holes, stumps, logs, and artificial containers, such as discarded tires.
• They are often the first mosquito noticed in spring, and later after heavy rainfall.
• Adults emerging together from flooded areas are often so numerous that natural controls, such as predators and parasites, are overwhelmed.
• Unlike some other Aedes mosquitoes, inland floodwater mosquitoes may fly more than 10 miles from their larval development sites in search of blood meals.

MOSQUITO-BORNE ENCEPHALITIS DISEASES

• The cycles of mosquito-borne viral encephalitis and meningitis diseases are similar.
• Most involve various bird species that are said to bereservoirs.
• Once infected by a mosquito bite, the reservoir species are usually not seriously affected.
• They will, at least for a time, produce enough virus in their bodies to infect mosquitoes. 
• In this manner, mosquitoes pick up the virus and may become vectors, or organisms that transmit the disease to other animals, such as birds, horses or humans.
• Horses and humans are generally thought of as “dead-end” hosts because they do not produce enough virus to infect mosquitoes.
• Thus, dead-end hosts are not involved in the spread of disease.
• nfall and temperature.

EASTERN and WESTERN EQUINE ENCEPHALITIDES

• Outbreaks of these related encephalitis viruses are rare.
• Several different mosquito species are suspected vectors of Eastern equine encephalitis, while Culex tarsalis, known as the western encephalitis mosquito, is the vector of Western equine encephalitis.
• Their uncommon occurrence is fortunate because, of all encephalitides, the equine encephalitides may have the highest potential for human mortality.

PREVENTING MOSQUITO BITES

• One strategy to prevent mosquito bites is avoidance.
• But even if one were to remain indoors throughout the mosquito season, they might still encounter mosquitoes.
• Mosquitoes, such as the house mosquito, are adept at getting into structures to feed on the inhabitants, and also to use crawlspaces, basements and cellars as quiet spots in which to shelter themselves for the winter.
• It is important to keep structures in good repair, maintaining the integrity of window and door screens and weather stripping, and screening or sealing all gaps through which mosquitoes might enter, such as spaces around utility lines, vents, foundation cracks, and gaps around windows and doors.
• Repellents are the first line of defense against mosquito bites. Many products provide some degree of protection against mosquito bites

MANAGING MOSQUITOES

• Historically the most effective mosquito control has been larviciding, which is the application of pesticides formulated to kill mosquito larvae before they become biting adults.
•  The Illinois Department of Public Health promotes mosquito control by advising and funding local health departments and other organizations that conduct larviciding, as well as mosquito surveillance.
• Surveillance includes the collection and identification of mosquitoes that helps predict mosquito and disease outbreaks and the focusing of control efforts in problem locations.

LARVICIDING

• Larvicides containing the insect growth regulator, methoprene, work by disrupting the larva’s metamorphosis, preventing it from developing into an adult.
• The toxicity of both types of larvicide is quite low, and both are considered safe to use in waters containing fish.
• These larvicides can be purchased at discount and hardware stores, and lawn and garden centers for private individuals to use on their property.