How Mosquitoes Work, HowStuffWorks

How Mosquitoes Work

Let’s say it’s summer time. You’re out in your backyard enjoying the sun and grilling your dinner. Ouch! You look down at your arm and see a painful, swelling mosquito bite. Moments later, you feel another one bite you. What are these pesky insects? Why do they bite? Do they carry diseases? What can you do to protect yourself

In this article, we’ll take a close-up look at mosquitoes — how they breed, how they bite, what diseases they carry and what you can do to control them.

Up Close

Mosquitoes are insects that have been around for more than 30 million years. And it seems that, during those millions of years, mosquitoes have been honing their skills so that they are now experts at finding people to bite. Mosquitoes have a battery of sensors designed to track their prey, including:

  • Chemical sensors — mosquitoes can sense carbon dioxide and lactic acid up to 100 feet (36 meters) away. Mammals and birds gives off these gases as part of their normal breathing. Certain chemicals in sweat also seem to attract mosquitoes (people who don’t sweat much don’t get nearly as many mosquito bites).
  • Visual sensors — if you are wearing clothing that contrasts with the background, and especially if you move while wearing that clothing, mosquitoes can see you and zero in on you. It’s a good bet that anything moving is «alive», and therefore full of blood, so this is a good strategy.
  • Heat sensors — Mosquitoes can detect heat, so they can find warm-blooded mammals and birds very easily once they get close enough.

Something with this many sensors sounds more like a military aircraft than an insect. That’s why mosquitoes are so good at finding and biting you. As we’ll see later, one of the only ways to stop mosquitoes from finding you is to confuse their chemical receptors with something like DEET.

Like all insects, adult mosquitoes have three basic body parts:

  • Head — This is where all the sensors are, along with the biting apparatus. The head has two compound eyes, antennae to sense chemicals and the mouth parts called the palpus and the proboscis (only females h­ave the proboscis, for biting).
  • Thorax — This segment is where the two wings and six legs attach. It contains the flight muscles, compound heart, some nerve cell ganglia and ­trachioles.
  • Abdomen — This segment contains the digestive and excretory organs.

So you have a sensor package, a motor package and a fuel processing package — a perfect design!

We’ll look at the different types of mosquitoes in the next section.


Few animals on Earth evoke the antipathy that mosquitoes do. Their itchy, irritating bites and nearly ubiquitous presence can ruin a backyard barbecue or a hike in the woods. They have an uncanny ability to sense our murderous intentions, taking flight and disappearing milliseconds before a fatal swat. And in our bedrooms, the persistent, whiny hum of their buzzing wings can wake the soundest of sleepers.

Beyond the nuisance factor, mosquitoes are carriers, or vectors, for some of humanity’s most deadly illnesses, and they are public enemy number one in the fight against global infectious disease. Mosquito-borne diseases cause millions of deaths worldwide every year with a disproportionate effect on children and the elderly in developing countries.

There are more than 3,000 species of mosquitoes, but the members of three bear primary responsibility for the spread of human diseases. Anopheles mosquitoes are the only species known to carry malaria. They also transmit filariasis (also called elephantiasis) and encephalitis. Culex mosquitoes carry encephalitis, filariasis, and the West Nile virus. And Aedes mosquitoes, of which the voracious Asian tiger is a member, carry yellow fever, dengue, and encephalitis.

Mosquitoes transmit disease in a variety of ways. In the case of malaria, parasites attach themselves to the gut of a female mosquito and enter a host as she feeds. In other cases, such as yellow fever and dengue, a virus enters the mosquito as it feeds on an infected human and is transmitted via the mosquito’s saliva to a subsequent victim.

Mosquitoes use exhaled carbon dioxide, body odors and temperature, and movement to home in on their victims. Only female mosquitoes have the mouth parts necessary for sucking blood. When biting with their proboscis, they stab two tubes into the skin: one to inject an enzyme that inhibits blood clotting; the other to suck blood into their bodies. They use the blood not for their own nourishment but as a source of protein for their eggs. For food, both males and females eat nectar and other plant sugars.

Impact on the Ecosystem

The only silver lining to that cloud of mosquitoes in your garden is that they are a reliable source of food for thousands of animals, including birds, bats, dragonflies, and frogs. In addition, humans are actually not the first choice for most mosquitoes looking for a meal. They usually prefer horses, cattle, and birds.

All mosquitoes need water to breed, so eradication and population-control efforts usually involve removal or treatment of standing water sources. Insecticide spraying to kill adult mosquitoes is also widespread. However, global efforts to stop the spread of mosquitoes are having little effect, and many scientists think global warming will likely increase their number and range.

Mosquito Bites


Mosquitoes are insects that live all over the world. There are thousands of different species of mosquitoes; about 200 of those live in the United States.

Female mosquitoes bite animals and humans and drink a very small amount of their blood. They need protein and iron from blood to produce eggs. After drinking blood, they find some standing water and lay their eggs in it. The eggs hatch into larvae, then pupae, and then they become adult mosquitos. The males live for about a week to ten days, and the females can live up to several weeks. Some female mosquitoes can hibernate in the winter, and they can live for months.

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What health problems can mosquito bites cause?

Most mosquito bites are harmless, but there are times when they can be dangerous. The ways that mosquito bites can affect humans include

  • Causing itchy bumps, as an immune system response to the mosquito’s saliva. This is the most common reaction. The bumps usually go away after a day or two.
  • Causing allergic reactions, including blisters, large hives, and in rare cases, anaphylaxis. Anaphylaxis is a severe allergic reaction that affects the whole body. It is a medical emergency.
  • Spreading diseases to humans. Some of these diseases can be serious. Many of them do not have any treatments, and only a few have vaccines to prevent them. These diseases are more of a problem in Africa and other tropical areas of the world, but more of them are spreading to the United States. One factor is climate change, which makes the conditions in some parts of the United States more favorable to certain types of mosquitoes. Other reasons include increased trade with, and travel to, tropical and subtropical areas.

Which diseases can mosquitoes spread?

Common diseases spread by mosquitoes include

  • Chikungunya, a viral infection that causes symptoms such as fever and severe joint pain. The symptoms usually last about a week, but for some, the joint pain may last for months. Most cases of chikungunya in the United States are in people who traveled to other countries. There have been a few cases where it has spread in the United States.
  • Dengue, a viral infection that causes a high fever, headaches, joint and muscle pain, vomiting, and a rash. Most people get better within a few weeks. In some cases, it can become very severe, even life-threatening. Dengue is rare in the United States.
  • Malaria, a parasitic disease that causes serious symptoms such as high fevers, shaking chills, and flu-like illness. It can be life-threatening, but there are drugs to treat it. Malaria is a major health problem in many tropical and subtropical areas of the world. Almost all cases of malaria in the United States are in people who traveled to other countries.
  • West Nile Virus (WNV), a viral infection that often has no symptoms. In those that do have symptoms, they are usually mild, and include fever, headache, and nausea. In rare cases, the virus can enter the brain, and it can be life-threatening. WNV has spread across the continental United States.
  • Zika Virus, a viral infection that often does not cause symptoms. One in five infected people do get symptoms, which are usually mild. They include a fever, rash, joint pain, and pinkeye. Besides being spread by mosquitoes, Zika can spread from mother to baby during pregnancy and cause serious birth defects. It can also spread from one partner to another during sex. There have been a few outbreaks of Zika in the southern United States.


Almost everyone has had the unpleasant experience of being bitten by a mosquito. Mosquito bites can cause skin irritation through an allergic reaction to the mosquito’s saliva — this is what causes the red bump and itching. But a more serious consequence of some mosquito bites may be transmission of serious diseases and viruses such as malaria, dengue virus, Zika and West Nile virus, which can lead to disabling and potentially deadly effects (such as encephalitis, meningitis and microcephaly). Read more about diseases carried by mosquitoes.

Not only can mosquitoes carry diseases that afflict humans, but they also can transmit several diseases and parasites that dogs and horses are very susceptible to. These include dog heart worms, eastern equine encephalitis and West Nile virus.

There are about 200 different species of mosquitoes in the United States, which live in specific habitats, exhibit unique behaviors and bite different types of animals. Despite these differences, all mosquitoes share some common traits, such as a four-stage life cycle (egg, larva, pupa, adult).

Different species of mosquitoes prefer different types of standing water in which to lay their eggs. The presence of beneficial predators such as fish and dragonfly nymphs in permanent ponds, lakes and streams help keep these bodies of water relatively free of mosquito larvae. However, portions of marshes, swamps, clogged ditches and temporary pools and puddles are all prolific mosquito breeding sites. Other sites in which some species lay their eggs include:

  • tree holes,
  • old tires,
  • buckets,
  • toys,
  • potted plant trays and saucers,
  • plastic covers or tarpaulins and even
  • places as small as bottle caps!

Some of the most annoying and potentially dangerous mosquito species, such as the Asian tiger mosquito, come from these sites.

To control mosquito populations and help prevent the spread of diseases they can carry, learn how to prevent mosquitoes by:

EPA and the Centers for Disease Control and Prevention (CDC) work closely with each other and with other federal, state, and local agencies to protect the public from mosquito-borne diseases such as Zika and the West Nile virus. CDC, working closely with state and local health departments, monitors the potential sources and outbreaks of mosquito-borne diseases and provides advice and consultation on prevention and control of these diseases. EPA ensures that state and local mosquito control departments have access to effective mosquito control tools that they can use without posing unreasonable risk to human health and the environment.

State and local government agencies play a critical role in protecting public health from mosquito-borne diseases. They serve on the front line, providing information through their outreach programs to the medical and environmental surveillance networks that first identify possible outbreaks. They also manage the mosquito control programs that carry out prevention, public education and vector population management. These agencies determine if the use of pesticides for mosquito control is appropriate for their area.

Learn more about:

Zika Virus

For current information on the Zika virus, please visit the CDC Zika Virus website. CDC also has information on:

Contact Us to ask a question, provide feedback, or report a problem.


Did you know? Only female mosquitoes bite humans.

Mosquito Facts for Kids

There are about 170 different kinds of mosquitoes in North America alone. These pests are part of the same family as houseflies and fruit flies, because they all have two clear, veined wings.

Best known as a summer pest, Mosquitoes can develop from egg to adult in 10 to 14 days.

  • Size: 1/4″ to 3/8″
  • Shape: Narrow, oval
  • Color: Pale brown with whitish stripes across abdomen.
  • Legs: 6
  • Wings: Yes
  • Antenna: Yes
  • Common Name: Mosquito
  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Class: Insecta
  • Order: Diptera
  • Family: Culicidae
  • Species: Varies

We usually say, «I have been bitten by a mosquito», but this is not completely true. In fact, mosquitoes do not bite. Female mosquitoes feed on plant nectar and blood. They need the protein to reproduce. To get to the blood, they pierce our skin with their » proboscis » and suck our blood. Male mosquitoes feed exclusively on plant nectars. Mosquitoes are busiest at night and will fly up to 14 miles for a blood meal. They hunt for food by detecting body heat and Carbon Dioxide , the gas we breathe out.

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Mosquitoes breed in soft, moist soil or stagnant water sources such as storm drains, old tires, children’s wading pools and birdbaths.


Mosquitoes spread diseases such as West Nile Virus , malaria and dengue fever .


  • Replace all stagnant water at least once a week.
  • Remove trash from around any standing water.
  • When sleeping outdoors or in areas where mosquito populations are heavy, surround your bed with «mosquito» netting.
  • Screen windows, doors and other openings with fine mesh.
  • Avoid going outdoors at night.
  • Use insect repellent containing DEET on exposed skin anytime you’re around mosquitoes. DEET doesn’t kill the mosquitoes. It just disorients them and they look elsewhere for food.

Didn’t find the facts you were looking for on PestWorld for Kids? Get information on mosquito management at the official NPMA website.

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How to Kill Mosquitoes: What Works and What Doesn’t

Separating Mosquito Control Fact From Fiction

  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College

Mosquitoes bite, suck your blood, and leave you with itchy bumps and possibly a horrible infection. Mosquito-borne pathogens include malaria, West Nile virus, Zika virus, Chikungunya virus, and dengue.

While you might fantasize about living in a mosquito-free world, eradicating them would actually be disastrous for the environment. Adult mosquitoes are food for other insects, birds, and bats, while larval mosquitoes support aquatic ecosystems. The best we can hope for is to limit their ability to transmit disease, repel them, and kill them within the confines of our yards and homes.

Mosquito-killing products bring in the big bucks, so it should come as no surprise that there is a wealth of misinformation out there. Before you get sucked into buying a product that simply won’t work, get educated about what does and does not kill these blood-sucking pests.

Key Takeaways: How to Kill Mosquitoes

  • The best way to kill and control mosquitoes is to consistently apply more than one method. Some methods may only target adults, while others may only target larvae.
  • Effective ways to kill mosquitoes include removing breeding grounds, encouraging predators, applying an agent containing BTI or IGR, and using traps.
  • Insect repellents and bug zappers don’t kill mosquitoes.
  • Pesticide-resistant mosquitoes may survive spraying, plus the chemical kills other animals and may persist in the environment.

How Not to Kill Mosquitoes

First, you need to understand the difference between repelling mosquitoes and killing them. Repellents make a location (like your yard or skin) less attractive to mosquitoes, but don’t kill them. So, citronella, DEET, smoke, lemon eucalyptus, lavender, and tea tree oil might keep the insects at bay, but won’t control them or get rid of them in the long run. Repellents vary in effectiveness, too. For example, while citronella may deter mosquitoes from entering a small, enclosed area, it doesn’t really work in a wide open space (like your back yard).

There are a host of methods that actually do kill mosquitoes, but aren’t great solutions. A classic example is a bug zapper, which kills only a few mosquitoes, yet attracts and kills beneficial insects that keep the mozzy population down. Similarly, spraying pesticides is not an ideal solution because mosquitoes can become resistant to them, other animals get poisoned, and the toxins can cause lasting environmental damage.

Source Reduction

Many species of mosquitoes required standing water to breed, so one of the most effective methods of controlling them is to remove open containers and repair leaks. Dumping containers of standing water kills the larvae living in them before they get a chance to mature.

However, removing water may be undesirable or impractical in some cases. Further, some species don’t even need standing water to reproduce! The Aedes species, responsible for transmitting Zika and dengue, lays eggs out of water. These eggs remain viable for months, ready to hatch when sufficient water becomes available.

Biological Methods

A better solution is to introduce predators that eat immature or adult mosquitoes or infectious agents that harm mosquitoes without affecting other wildlife.

Most ornamental fish consume mosquito larvae, including koi and minnows. Lizards, geckos, dragonfly adults and naiads, frogs, bats, spiders, and crustaceans all eat mosquitoes.

Adult mosquitoes are susceptible to infection by the fungi Metarhizium anisoplilae and Beauveria bassiana. A more practical infectious agent is the spores of the soil bacterium Bacillus thurigiensis israelensis (BTI),. Infection with BTI makes the larvae unable to eat, causing them to die. BTI pellets are readily available at home and gardening stores, easy to use (simply add them to standing water), and only affect mosquitoes, black flies, and fungus gnats. The treated water remains safe for pets and wild animals to drink. The disadvantages of BTI are that it requires reapplication every week or two and it doesn’t kill adult mosquitos.

Chemical and Physical Methods

There are several chemical methods that target mosquitoes without the risks to other animals that come with spraying pesticides.

Some methods rely on chemical attractants to lure mosquitoes to their doom. Mosquitoes are attracted to carbon dioxide, sugary scents, heat, lactic acid, and octenal. Gravid females (those carrying eggs) may be attracted to traps laced with a hormone released during the egg-laying process.

The lethal ovitrap is dark, water-filled container, typically with a small opening to prevent larger animals from drinking the water. Some traps use chemicals to bait the traps, while others simply provide a convenient breeding ground. The traps may be filled with predators (e.g., fish) or with dilute pesticide to kill larvae (larvicide) and sometimes adults. These traps are highly effective and affordable. The disadvantage is that multiple traps must be used to cover an area (about one every 25 feet).

Another chemical method is the use of an insect growth regulator (IGR), added to water to inhibit larval development. The most common IGR is methoprene, which is supplied as a time-release brick. While effective, methoprene has been shown to be mildly toxic to other animals.

See also:  WHO, Control strategies

Adding a layer of oil or kerosene to water kills mosquito larvae and also prevents females from depositing eggs. The layer alters the surface tension of the water. Larvae can’t get their breathing tube to the surface for air, so they suffocate. However, this method kills other animals in the water and makes the water unfit for consumption.

Physical Methods

One example of a physical method of killing mosquitoes is swatting them with your hand, a fly-swatter, or an electric swatter. Swatting works if you’ve only got a few mosquitoes, but it’s not particularly helpful if you’re being swarmed. While bug zappers aren’t ideal outdoors because they can unnecessarily kill beneficial insects, electrocuting indoor insects isn’t generally considered objectionable. Just remember, you need to bait a bug zapper to attract mosquitoes, because they don’t care about the pretty blue light.

Because mosquitoes are not strong fliers, it’s also easy to suck them onto a screen or into a separate trap using a fan. Mosquitoes caught using a fan die from dehydration. Screen-traps may be made at home by fastening window screening fabric over the back of a fan.

The Bottom Line

If you’re serious about killing mosquitoes, you’ll probably need to use a combination of methods to control them. Some of the most effective strategies target either the larvae or the adult. Others kill mosquitoes at all stages of their life cycle, but may miss some of the insects.

If you live in a wetland area and get a significant influx of mosquitoes from outside your property, you won’t be able to kill all of the local population. Don’t despair! Scientists are developing ways to make mosquitoes sterile or lay eggs that won’t mature. In the meanwhile, you’ll need to combine repellents with lethal measures to enjoy the outdoors.

Prevent Mosquito Bites

The most effective way to avoid getting sick from viruses spread by mosquitoes when at home and during travel is to prevent mosquito bites.

Mosquito bites can be more than just annoying and itchy. They can spread viruses that make you sick or, in rare cases, cause death. Although most kinds of mosquitoes are just nuisance mosquitoes, some kinds of mosquitoes in the United States and around the world spread viruses that can cause disease.

Mosquitoes bite during the day and night, live indoors and outdoors, and search for warm places as temperatures begin to drop. Some will hibernate in enclosed spaces, like garages, sheds, and under (or inside) homes to survive cold temperatures. Except for the southernmost states in North America, mosquito season starts in the summer and continues into fall.

Examples of viruses spread by mosquitoes:

When used as directed, insect repellents are the BEST way to protect yourself and family members from getting sick from mosquito bites.


  • Use insect repellent: When used as directed, Environmental Protection Agency (EPA)-registered insect repellents are proven safe and effective, even for pregnant and breastfeeding women. Use an EPA-registered insect repellent External with one of the following active ingredients:
    • DEET
    • Picaridin
    • IR3535
    • Oil of lemon eucalyptus (OLE)
    • Para-menthane-diol (PMD)
    • 2-undecanone
  • Cover up: Wear long-sleeved shirts and long pants.
  • Keep mosquitoes outside: Use air conditioning, or window and door screens. If you are not able to protect yourself from mosquitoes inside your home or hotel, sleep under a mosquito bed net.

Planning a trip?

Make a check list of everything you’ll need for an enjoyable vacation and use the following resources to help you prepare.

  • Learn about destination-specific health risks and recommendations by visiting CDC Travelers’ Health website.
  • Pack a travel health kit. Remember to pack insect repellent and use it as directed to prevent mosquito bites.
  • See a healthcare provider familiar with travel medicine, ideally 4 to 6 weeks before your trip.
  • Go to the Find a Clinic webpage for help in finding a travel medicine clinic near you.

For most viruses spread by mosquitoes, there are no vaccines or medicines available. However, vaccines are available for viruses like Japanese encephalitis and yellow fever. Travelers to areas with risk of those viruses should get vaccinated.

After traveling

  • Even if they do not feel sick, travelers should prevent mosquito bites for 3 weeks after their trip so they do not spread viruses like dengue, Zika, or chikungunya to uninfected mosquitoes.
  • If you have been travelling and have symptoms including fever, headache, muscle and joint pain, and rash, see your healthcare provider immediately and be sure to share your travel history.

Mosquito-borne viruses in the continental US

West Nile virus is the most common virus spread by mosquitoes in the continental United States. People can also get sick from less common viruses spread by mosquitoes, like La Crosse encephalitis or St. Louis encephalitis. In rare cases, these can cause severe disease or even be deadly. Most people infected with these viruses do not have symptoms, or have only mild symptoms like fever, headache, nausea, and vomiting. CDC tracks diseases spread by mosquitoes.

Mosquito-borne viruses in US territories

Viruses like dengue, Zika, and chikungunya are well-known to people living in US territories like Puerto Rico and the US Virgin Islands. Many people infected with these viruses do not have symptoms, or have mild symptoms. Mild symptoms can include fever, headache, muscle and joint pain, and rash.

More than one-third of the world’s population lives in areas with risk of dengue, including Puerto Rico. Dengue virus infections are a leading cause of illness and death in the tropics and subtropics. It is estimated as many as 100 million people get sick each year. Dengue is caused by any one of four related viruses spread by mosquitoes. Early recognition and prompt medical care can greatly lower the risk of complications and even death. Learn more from the Dengue Feature.

Zika virus disease (Zika) is still a problem in many parts of the world. Puerto Rico and US Virgin Islands are areas with risk. Many areas in the United States have the kind of mosquitoes that can spread Zika.

Zika can cause birth defects in babies born to women who were infected during pregnancy. CDC recommends pregnant women and their partners and couples considering pregnancy know the risks and take prevention steps.

Since 2013, chikungunya virus has spread to 45 countries and over 2 million cases have been reported. US territories such as Puerto Rico and the US Virgin Islands have had large outbreaks of chikungunya virus. Infection is rarely fatal, but joint pain can often be severe and debilitating. There are also cases of travelers returning home who have been infected.

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