Mosquitoes, their bites and the diseases they carry

Updated on November 26th, 2024

Ah, mosquitoes. These pesky insects are a nuisance to many, while deadly to others. Mosquitoes are small, flying insects that belong to the family Culicidae. They are found all over the world, from the tropics to the arctic. During peak breeding season, they outnumber every other animal on Earth, minus termites and ants. When it comes to killing humans, no other creature even comes close, not even snakes (and definitely not sharks), to the mosquito—according to Centers for Disease Control and Prevention (CDC).

Where are mosquitoes most common in the U.S.?

Mosquitoes can be found throughout the United States, but some regions experience higher populations than others. These pesky insects thrive in warm and humid environments, particularly areas with abundant standing water and high temperatures. Mosquito-mamas lay eggs just above the waterline in wet containers, thriving in humid, water-rich environments.

Certain cities in the U.S. are particularly prone to mosquitoes and their bites. Based on data from April 2018 to March 2019 by Consumer Affairs, the top 10 mosquito hotspots include:

• Atlanta, GA     
• New York City, NY             
• Washington, D.C.
• Chicago, IL
• Houston, TX
• Dallas-Ft. Worth, TX
• Detroit, MI
• Philadelphia, PA
• Charlotte, NC
• Raleigh-Durham, NC

If you live in or visit one of these cities, taking extra precautions to prevent mosquito bites is essential, especially during peak mosquito seasons.

Where are mosquito-borne diseases most common?

Mosquito-borne diseases are most common in tropical and subtropical regions of the world, including parts of Africa, South and Central America, the Caribbean, Southeast Asia and Oceania. These regions have suitable environmental conditions for mosquitoes to thrive and spread diseases, and often have limited resources and infrastructure to control mosquito populations and prevent disease transmission.

For example, malaria, a most serious disease caused by a parasite that is transmitted to humans through the bites of infected female mosquitoes, is intimately and harshly intertwined with poverty.

As T. H. Weller, a Nobel laureate in medicine, once said, "It has long been recognized that a malarious community is an impoverished community." And it's not just communities, but entire countries that suffer from the burden of malaria. In Africa, the poorest continent, malaria is especially unyielding. The only parts of Africa that are free of malaria are the northern and southern extremes, which happen to have the richest countries on the continent.

It's not just Africa, either. India, a country with a large number of people in poverty, has a serious malaria problem.

When do mosquitoes bite?

Mosquitoes are most likely to bite during dawn and dusk, as these twilight hours provide ideal conditions, avoiding the heat and dehydration risks of direct sunlight.

However, not all mosquito species stick to this schedule. For example, the Aedes aegypti mosquito, which can transmit diseases like Zika and dengue, is known for being a daytime biter, often targeting people during mid-morning and late afternoon. In contrast, Culex mosquitoes, which spread West Nile virus, tend to prefer nighttime biting.

Can mosquitoes bite through clothing? Through jeans?

Mosquitoes are persistent, and their bites can sometimes occur even through clothing. Thin, tight-fitting fabrics—like spandex or lightweight cotton—may not provide sufficient protection, as some mosquito species—like the Aedes aegypti—have been known to bite through these materials. 

That said, thicker fabrics such as denim and jeans are generally mosquito-proof. The dense weave of denim makes it difficult for a mosquito’s proboscis to penetrate.

Note: For the best protection, choose loose-fitting, tightly woven clothing and combine it with repellents to cover exposed areas.

Do mosquitoes die after biting?

Unlike bees, mosquitoes do not die after biting. Female mosquitoes need a blood meal to lay eggs, and once they’ve fed, they can bite again after digesting the blood. This ability to bite multiple times increases their capacity to spread diseases like malaria, dengue and Zika.

You don’t need to worry about male mosquitoes biting you—they’re harmless to humans. Male mosquitoes feed exclusively on plant nectar and other sweet substances, playing no role in disease transmission. Male mosquitoes typically perish after mating, surviving only a week to 10 days.

Female mosquitoes, however, live longer lives—usually around 6 weeks. They die after completing several reproductive cycles, which include feeding on blood, laying eggs and repeating the process. Their longevity and ability to bite multiple times make them far more dangerous in transmitting diseases.

When are different types of mosquitoes most active?

Generally speaking, mosquitoes tend to be more active during warmer months when temperatures are above 50° F. In the United States, different species of mosquitoes may be active at different times of the year, depending on the region. For example, in the southern states, mosquitoes can be active year-round, while in the northern states, mosquito activity is typically limited to the summer months. 

Different species of mosquitoes are active at varying times. For instance, Aedes aegypti, known for transmitting Zika and dengue, prefers daytime biting, often during mid-morning and late afternoon. In contrast, Culex mosquitoes, which spread West Nile virus, are primarily active at night.

What viruses and diseases do mosquitoes transmit?

Mosquitoes are known to transmit a variety of viruses and diseases to humans, including:

1. Malaria: A life-threatening disease caused by parasites that are transmitted to humans through the bites of infected female mosquitoes (not their male counterparts) of the Anopheles species.
2. Dengue fever: A viral infection that is spread by the Aedes aegypti mosquito and can cause a high fever, severe headaches, joint and muscle pain and skin rash.
3. Zika virus: A virus spread by the Aedes mosquito that can cause fever, rash, joint pain and conjunctivitis, and is especially dangerous for pregnant women as it can cause birth defects.
4. Yellow fever: A viral disease that is transmitted by the Aedes or Haemagogus mosquito and can cause fever, muscle pain and jaundice.
5. West Nile virus: A virus that is spread by infected mosquitoes and can cause flu-like symptoms, fever and in severe cases, inflammation of the brain and spinal cord.
6. Chikungunya: A viral disease that is spread by the Aedes mosquito and can cause fever, joint pain, muscle pain, headache and rash.
7. Encephalitis: A viral infection that can cause inflammation of the brain and is transmitted by mosquitoes of the Culex species.

According to WHO, malaria alone—a disease that greatly limits human potential—"results in more than 400,000 deaths every year," whereas "more than 3.9 billion people in over 129 countries are at risk of contracting dengue." Dengue, the most prevalent viral infection transmitted by Aedes mosquitoes, is responsible for an "estimated 40,000 deaths every year."

How the Panama Canal revolutionized mosquito control

Interestingly enough, the construction of the Panama Canal helped to lead the way in combating mosquito-borne illnesses. In the early 1900s, construction crews worked to construct a waterway through nature and nature aggressively fought back. The snake-infested jungle in which these crews worked, with an average temperature of 80° F and 105 inches of rainfall a year, provided an ideal breeding ground for mosquitoes and, subsequently, a very deadly spot in the world in which to construct a channel.

An article by Christopher Klein, published in History tells us that "Over the span of more than three decades, at least 25,000 workers died in the construction of the Panama Canal" whereas a further History article by Elizabeth Nix informs us that many of these deaths were "caused by yellow fever and malaria, diseases that the medical community at the time believed were caused by bad air and dirty conditions."

This deadly environment prompted groundbreaking public health efforts led by Dr. William C. Gorgas, who implemented large-scale mosquito control measures like draining standing water, using oil to coat water surfaces and installing protective screens. These methods helped reduce the spread of disease and laid the foundation for modern mosquito control strategies still used today.

What can mosquito bites cause in cats & dogs? 

While humans are the primary victims of mosquito bites, pets like cats and dogs are not immune. Mosquito bites in pets can cause skin irritation, allergic reactions or more serious conditions like heartworm disease, which is transmitted by infected mosquitoes. Heartworm disease, in particular, can be life-threatening for pets if left untreated.

The broader health implications of mosquito bites highlight the importance of protecting every member of your household—both humans and animals. Prevention measures such as heartworm medication, pet-safe mosquito repellents and eliminating standing water in outdoor areas are crucial for reducing the risks.

Consult your veterinarian about the best protective measures for your pets, ensuring they remain safe from mosquito-borne illnesses.

How do I get rid of and protect myself and my family from mosquitoes?

Here are six tips to help in both getting rid of and protecting yourself and your family from deadly mosquitoes in mosquito-infested areas. Some of these tips, according to CDC, were first implemented during the construction of the Panama Canal. 

1. Eliminate standing water: Mosquitoes need standing water to breed and produce their larvae, so it's important to eliminate any standing water around your home, such as in buckets, flower pots and bird baths. This will greatly aid in keeping mosquitoes away from your home and yard. 
2. Use a DIY mosquito repellent: Apply mosquito repellent to exposed skin, especially during peak mosquito hours. This can be for indoor or outdoor use.
3. Wear protective clothing: Wear long-sleeved shirts, pants and socks when spending time outdoors, especially in areas where mosquitoes are prevalent.
4. Use mosquito nets: Use mosquito nets over beds, baby cribs and strollers to protect against mosquito bites. These are highly recommended by WHO for pregnant women and young children.
5. Install screens: Make sure your windows and doors have screens to keep mosquitoes out of your home.
6. Keep your yard maintained: Trim shrubs and grass regularly and keep your yard free of debris to reduce potential mosquito breeding sites.