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What does a mosquito bite look like? Pretty ridiculous question for most people on planet earth!

For all but a few of us mammals living in the northern and southern extremes of the earth, the mosquito is a pesky creature we all have to deal with at some level in living our day to day lives.

The Mosquito Site is a site about these insects that we humans don’t really care for, the site is part entertainment and a whole lot informational. Please enjoy the site and come back often. 

Mosquitoes and Humans

Mosquitoes carry disease-causing pathogens from person to person without catching the disease themselves. Female mosquitoes suck blood from people and other animals as part of their eating and breeding habits. When a mosquito bites, she also injects saliva and anti-coagulant's into the blood which may also contain disease-causing viruses or other parasites.

Mosquitoes are estimated to transmit disease to more than 700 million people annually in Africa, South America, Central America, Mexico, and much of Asia with millions of resulting deaths. In Europe, Russia, Canada, the United States, Australia, Japan and other temperate and developed countries, mosquito bites are now mostly an irritating nuisance; but still cause some deaths each year.

Historically, before mosquito transmitted diseases were brought under control; they caused tens of thousands of deaths in these countries and hundreds of thousands of infections. Mosquitoes were shown to be the method by which yellow fever and malaria were transmitted from person to person by Walter Reed, William C. Gorgas and associates in the U.S. Army Medical Corps first in Cuba and then around the Panama Canal in the early 1900s. Since then other diseases have been shown to be transmitted the same way.

The mosquito genus Anopheles carries the malaria parasite (Plasmodium). Worldwide, malaria is a leading cause of premature mortality, particularly in children under the age of five, with around 5.3 million deaths annually, according to the Centers for Disease Control.

Eastern equine encephalitis (EEE) and Western equine encephalitis (WEE) occurs in the United States where it causes disease in humans, horses, and some bird species. Because of the high mortality rate, EEE and WEE are regarded as two of the most serious mosquito-borne diseases in the United States.

Symptoms range from mild flu-like illness to encephalitis, coma and death. Viruses carried by arthropods such as mosquitoes or ticks are known collectively as arbor viruses. West Nile virus was accidentally introduced into the United States in 1999 and by 2003 had spread to almost every state with over 3,000 cases in 2006.

 A mosquito's period of feeding is often undetected; the bite only becomes apparent because of the immune reaction it provokes. When a mosquito bites a human, she injects saliva and anti-coagulant's. For any given individual, with the initial bite there is no reaction but with subsequent bites the body's immune system develops antibodies and a bite becomes inflamed and itchy within 24 hours. This is the usual reaction in young children.

With more bites, the sensitivity of the human immune system increases, and an itchy red hive appears in minutes where the immune response has broken capillary blood vessels and fluid has collected under the skin. This type of reaction is common in older children and adults. Some adults can become desensitized to mosquitoes and have little or no reaction to their bites, while others can become hyper-sensitive with bites causing blistering, bruising, and large inflammatory reactions, a response known as Skeeter Syndrome.

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Mosquito - Biology

Anatomy

The mosquito is composed of a head, thorax, and abdomen. The head contains two compound eyes and proboscis. The proboscis is a piercing mouthpart used to suck blood from its prey. The mosquito's head is mostly eye. Each eye is made up of many tiny lenses forming a compound eye. This type of eye allows a very big field of vision that easily detects movement. Next is the thorax. The thorax has one pair of wings and one pair of halters. The thorax also has markings that are used in the identification of the mosquito. The abdomen, or gut, expands as it ingests its prey's blood. The abdomen also has many markings that are used to identify the mosquito species.

Life cycle and feeding habits

In its life cycle the mosquito undergoes  complete metamorphosis, going through four distinct stages:  egg , larva, pupa, and adult, first described by the Greek philosopher Aristotle.

Egg

Female mosquitoes lay their eggs one at a time or together in rafts of a hundred or more eggs on the surface in fresh or any stagnant water.  Anopheles and Aedes mosquitoes do not make egg rafts but lay their eggs separately. Culex, Culiseta, and Anopheles lay their eggs on water while Aedes  lay their eggs on damp soil that is periodically flooded by water. Most eggs hatch into larvae in about 48 hours. A female mosquito may lay a raft of eggs every third night during its life span if it can find enough blood to develop the eggs.

Larval stage

The hatching eggs turn into larvae that live in the water, coming to the surface to breathe. The first larval stage is known as the first instar. As they grow, they shed or moult their skin about four times, growing larger after each moulting. After the first molt they are second instars, then third, then fourth.

Most larvae use siphon tubes going to the water surface for breathing and hang on or near the water surface. Anopheles larvae do not have a siphon and typically lie parallel to the water surface. The larvae eat micro-organisms and organic matter in the water for food. Mosquito larvae, commonly called "wiggler's" or "wrigglers", must live in water from 7 to 14 days depending on the water's temperature.

At their last moult they may be up to 1 cm or 1/2 inch long. In each stage they may be eaten by other insects or fish. Mosquito larvae in the genus Toxorhynchites eat other mosquito larvae.

Culex mosquito larvae

The length of the first three stages (or instars) is dependent on the species and temperature, with lower temperatures increasing the length of the development stage. Culex tarsalis may complete its life cycle in 14 days at 20 C (68 F) and only ten days at 25 C (77 F). Some species have a life cycle of as little as four days, whereas in other species some adult females can live through the winter, laying their eggs in the spring.

Many species of mosquito live their adult stage in roughly two weeks to two months. The larvae are the "wrigglers" found in puddles or water-filled containers. These breathe air through a siphon at the tail end. The pupae, or "tumblers", are nearly as active as the larvae, but breathe through thoracic "horns" attached to the thoracic spiracles. Most larvae feed on micro-organisms, but a few are predatory on other mosquito larvae.

Pupa

The pupae are lighter than water and float on the surface as the mosquito larva metamorphoses (changes) into an adult mosquito in about two days. Pupae do not have mouths and therefore do not feed. This is important to know from a larviciding point of view because most larvicide has to be ingested by the mosquito. A surface oil or mmf (mono molecular film) should be applied to the breeding site as a means of suffocating the pupa.

Adult

The newly emerged adult must rest on the surface of the water for a short time to allow itself to dry and all its parts to harden before it can fly. This requires still water: mosquitoes do not breed in fast-moving water.

The total time to go through all four stages depends on the temperature and the type of mosquito, but typically takes 14 days or less in warmer weather. In various species the time varies from 4 to 30 days.

Most mosquito species outside of the tropics over winter as eggs, but many over winter as larvae or adults. Mosquitoes of the genus Culex (a vector for St. Louis encephalitis) over winter as mated adult females.

Most mosquitoes stay fairly close to the ground and do not range too far from where they were born, but may be dispersed long distances by wind. Mosquitoes are not strong flyers, making only 1-2 km/h (1-1.5 mph); therefore, an electric fan may suffice as an effective mosquito screen. They feed mostly in the mornings and evenings and occasionally at night, avoiding the heat of the day. During the day they usually find somewhere cool to rest. Mosquitoes can tend to live over puddled water or grassy areas.

Mosquito Feeding

Only female mosquitoes bite animals to get blood needed to produce eggs. Male mosquitoes do not bite, but both the male and female feed on the nectar of flowers for food. In most female mosquitoes, the mouth parts form a long proboscis for piercing the skin of mammals (or in some cases birds or even reptiles and amphibians) to suck their blood. As opposed to a syringe's typically smooth needle, the mosquito proboscis is highly serrated, which leaves a minimal number of points of contact with the skin being pierced — this reduces nerve stimulation to the point where the "bite" is typically not felt at all.

The females require protein for egg development and laying, and since the normal mosquito diet consists of nectar and fruit juice, which has no protein, most females must drink blood to lay eggs. Males differ from females, with mouth parts not suitable for blood-sucking.

  James Gathany 05

An Armigeres subalbatus mosquito ingesting a blood meal from a human finger. Note the mosquito's blood filled stomach and the blood being suctioned through it's proboscis.

The female mosquitoes locate their next blood donor victims primarily through scent. They are extremely sensitive to the carbon dioxide in exhaled breath, as well as to substances found in sweat and various body odors such as 1-octen-3-ol. They are believed to be able to track potential prey for tens of meters.

Some people attract more mosquitoes than others, apparently based on how they "smell" to a mosquito. Mosquitoes can also detect heat, so they can find warm-blooded mammals and birds very easily once they get close enough. Repellent's like DEET work by disorienting the mosquito as it gets close to its potential next meal but do not kill mosquitoes. Reports indicate at least a respectable rate of success with the use of these repellent's.

Male mosquitoes may tend to be smaller than females, with features such as feathered antennae and conspicuous external genitalia.

Mosquito Control

There are two kinds of mosquito control: large, organized programs to reduce mosquito populations over a wide area, and actions individuals can take to control or exclude mosquitoes with respect to themselves and their own property.

Organized mosquito control programs today draw on the principles of  integrated pest management. An integrated mosquito control program typically includes the following measures, all guided by surveillance of mosquito populations and knowledge of the mosquito life cycle.

• source reduction - the removal of mosquito breeding habitats  
• habitat modification - manipulating habitats to reduce breeding or access  
• bio control   - introducing natural predators of mosquitoes  
• larvicide   - using pesticides to reduce larval populations  
• adulticide - using pesticides to reduce adult populations  

Some solutions for malaria control efforts in the third world are: mosquito nets, mosquito nets treated with insecticide (often  permethrin), and DDT. Nets are treated with insecticide because mosquitoes can sometimes get past an imperfect net. Insecticide-treated nets (ITN) are estimated to be twice as effective as untreated nets in preventing mosquito bites. Untreated mosquito nets are less expensive, and they are effective in protecting humans when the nets do not have any holes and are tightly sealed around the edges. Insecticide free nets do not adversely affect the health of natural predators such as dragonflies.

The role of DDT in combating mosquitoes has been the subject of considerable controversy. While some argue that DDT deeply damages biodiversity, others argue that DDT is the most effective weapon in combating mosquitoes and hence malaria. While some of this disagreement is based on differences in the extent to which disease control is valued as opposed to the value of biodiversity, there is also genuine disagreement amongst experts about the costs and benefits of using DDT. Moreover, DDT-resistant mosquitoes have started to increase in numbers, especially in tropics due to mutations, reducing the effectiveness of this chemical.

Raphael Carter 2001

Repellent's and other methods of controlling the Mosquito

One of the main, non-chemical ways to prevent mosquito bites is the mosquito net. Mosquito netting if properly used and maintained (no holes), provides the maximum possible personal protection against biting insects. In many areas of the world, mosquitoes are not only a nuisance, but also pose a serious health threat. Sleeping under a bed net is highly recommended by the  World Health Organization (WHO) and the U.S. Center for Disease Control (CDC), if staying in these areas.

One of the most popular chemical treatments is N, N-diethyl-meta-toluamide, commonly known as DEET. It has been used widely since its invention by the U.S. Department of Agriculture in 1945. However, DEET products have been widely used for many years but these products have occasionally been associated with some minor to moderate adverse reactions. DEET concentrations range from a low of about five percent up to 100 percent. Mosquitoes use carbon dioxide (CO₂) and 1-octen-3-ol from human and animal breath and sweat as odor cues and DEET inhibits the detection of the latter in insects.

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Other less commonly used mosquito repellent's include: catnip oil extract, nepetalactone   (no known credible tests), citronella 10% solution (84% effective for about 1 hour), or eucalyptus oil extract Soy bean oil.

Other commercial products offered for household mosquito "control" include small electrical mats, mosquito repellent vapor, DEE T-impregnated wrist bands, and mosquito coils containing a form of the chemical Allethrin. Mosquito-repellent candles containing citronella oil are sold widely in the U.S. All of these have been used with mixed reports of success and failure. Some claim that plants like wormwood or sagewort, lemon balm, lemon grass, lemon thyme and the mosquito plant (Pelargonium) will act against mosquitoes. However, scientists have determined that these plants are “effective” for a limited time only when the leaves are crushed and applied directly to the skin.

There are several, widespread, unproven theories about mosquito control such as the assertion that Vitamin B, in particular B1 Thiamine, garlic, ultrasonic devices, incense, can be used to repel or control mosquitoes. Moreover, some manufacturers of "mosquito repelling" ultrasonic devices have been found to be fraudulent, and their devices were deemed "useless" in tests by a Consumer magazine.

The Dragonfly eats mosquitoes at all stages of development and is quite effective in controlling populations. Although bats and Purple Martins can be prodigious consumers of insects, many of which are pests, less than 1% of their diet typically consists of mosquitoes. Bats are known carriers of rabies, and neither they nor Purple Martins are known to control or even significantly reduce mosquito populations.

Similarly, bug zappers kill a wide range of flying insects including many beneficial insects that eat mosquitoes as well as some mosquitoes. Bug zappers have not been proven effective at controlling overall mosquito population.

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Some newer mosquito traps or known mosquito attractants emit a plume of carbon dioxide together with other mosquito attractants such as sugary scents, lactic acid, octenol, warmth, water vapor and sounds. By mimicking a mammal’s scent and outputs, female mosquitoes are drawn toward the trap, where they are typically sucked into a net or holder by an electric fan where they are collected. According to the American Mosquito Control Association, "these devices will, indeed, trap and kill measurable numbers of mosquitoes," but their effectiveness in any particular case will depend on a number of factors such as the size and species of the mosquito population and the type and location of the breeding habitat. They are useful in specimen collection studies to determine the types of mosquitoes prevalent in an area but are typically far too inefficient to be useful in reducing mosquito populations.

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