Which State Doesn't Have Mosquitoes? Unpacking the Myth and Reality of Mosquito-Free Zones

I remember a summer vacation to Montana, a state famed for its sweeping landscapes and majestic mountains. As we pitched our tents near a crystal-clear lake, I braced myself for the inevitable swarm of mosquitoes. Yet, to my surprise, the air remained remarkably still, with barely a buzz to be heard. This experience, while memorable, sparked a question that many people ponder: which state doesn't have mosquitoes? The short, and perhaps disappointing, answer is that there isn't a single U.S. state that is entirely mosquito-free. Every state, to some degree, harbors these ubiquitous insects. However, the perception of mosquito prevalence can vary wildly, and some regions are certainly far less hospitable to them than others.

My own encounters with mosquitoes have spanned the spectrum, from the ferocious swarms of the Florida Everglades, where a single exhale felt like an invitation, to the surprisingly tranquil evenings in the high desert of Arizona. These personal experiences, coupled with extensive research, have led me to understand that the absence of mosquitoes isn't a geographical certainty for any entire state, but rather a complex interplay of environmental factors, climate, and specific microhabitats.

The allure of a mosquito-free existence is understandable. These tiny pests are more than just a nuisance; they are vectors for serious diseases like West Nile virus, Zika virus, and Eastern Equine Encephalitis. For many, the dream of a vacation or even a permanent residence in a place devoid of these bloodsuckers is a powerful one. But does such a place exist within the continental United States? Let's delve into the intricate world of mosquito biology and geography to uncover the truth.

Understanding the Mosquito's Habitat Requirements

Before we can definitively address which states might have fewer mosquitoes, it's crucial to understand what makes a habitat ideal for them. Mosquitoes, like all living organisms, have specific needs for survival and reproduction. Their life cycle is intricately linked to water, and this is the single most important factor in determining their presence and abundance.

The mosquito life cycle consists of four stages: egg, larva, pupa, and adult. The first three stages are aquatic, meaning they occur in water. Female mosquitoes lay their eggs in or near water. Some species prefer stagnant, still water, such as ponds, puddles, and clogged gutters. Others are more opportunistic, laying eggs in floodwaters or even in small containers that can hold water, like discarded tires or birdbaths. These aquatic stages can last anywhere from a few days to several weeks, depending on water temperature and species.

Once the larval and pupal stages are complete, the adult mosquito emerges. The adult stage is where they become a nuisance to us. Adult mosquitoes require a food source, and while both males and females feed on nectar from plants for energy, only female mosquitoes bite animals and humans. They do this to obtain the protein necessary to develop their eggs. This biting behavior is what makes them problematic for us.

Therefore, for mosquitoes to thrive, they need:

Water sources: Essential for breeding grounds. This includes both large bodies of water and small, ephemeral collections.
Temperature: Mosquitoes are cold-blooded insects. Their activity levels are highly dependent on ambient temperature. Generally, they are most active in warm weather, typically between 70°F and 85°F (21°C to 29°C). Very cold temperatures can kill them or force them into dormancy.
Humidity: While not as critical as water, high humidity can help adult mosquitoes survive longer.
Vegetation: Provides resting places for adult mosquitoes and can offer shelter from wind and sun.

Considering these factors, it becomes clear why certain environments are more prone to mosquito infestations than others. Areas with abundant standing water, consistent warmth, and lush vegetation will naturally support larger mosquito populations. Conversely, environments that lack these conditions might have significantly fewer mosquitoes.

States with Naturally Low Mosquito Populations: The Dry and the Cold

When we search for states that don't have mosquitoes, we are essentially looking for states that have a limited number of the conditions listed above. The most significant factors that limit mosquito populations are dryness and extreme cold. States that are predominantly arid or experience harsh, prolonged winters tend to have fewer mosquitoes, especially during certain times of the year.

Arid States: States with very low annual rainfall and a lack of significant natural water bodies are prime candidates for having fewer mosquitoes. The primary limiting factor here is the absence of breeding grounds. Without standing water, the mosquito life cycle is severely hampered.

Nevada: Much of Nevada is desert, characterized by low humidity and scarce surface water. While there are some areas with water, such as Lake Tahoe and reservoirs, these are often managed and may not provide the ideal, undisturbed breeding conditions for many mosquito species. The vast majority of the state is simply too dry for large-scale mosquito proliferation.
Arizona: Similar to Nevada, large portions of Arizona are arid desert. The Sonoran and Mojave Deserts are not conducive to mosquito breeding. While monsoon seasons can create temporary water sources that lead to seasonal mosquito increases, the overall dry climate limits their year-round presence and abundance compared to more humid states.
New Mexico: Another state with significant arid and semi-arid regions. While rivers like the Rio Grande and some high-altitude lakes exist, large swathes of New Mexico are too dry to support substantial mosquito populations.
Utah: While Utah has the Great Salt Lake, much of the state's landscape is characterized by arid basins and mountainous regions. The dry climate limits the availability of standing water for breeding for much of the year.

Cold States: States that experience long, cold winters can effectively reset mosquito populations each year. Freezing temperatures kill off adult mosquitoes, and any overwintering eggs or larvae are also vulnerable. Mosquitoes in these regions are typically seasonal, emerging in large numbers only during the warmer months.

Alaska: This is perhaps the most commonly cited "mosquito-free" state, but it's a nuance. While Alaska has vast wilderness and numerous lakes and wetlands, which would suggest a mosquito paradise, its extremely cold climate plays a significant role. During the long winter, mosquitoes are virtually non-existent. However, during the brief but intense Arctic summer, mosquito populations can explode, becoming legendary for their sheer numbers and ferocity. So, while Alaska might be "mosquito-free" for a significant portion of the year, the summer months can be brutally buggy. It's a trade-off; you get beautiful, long daylight hours in the summer but with a serious insect price.
Hawaii: This might seem counterintuitive given its tropical climate. However, Hawaii has a unique situation. While it has plenty of rainfall and warm temperatures, which are ideal for mosquitoes, the native mosquito species are not found in Hawaii. The mosquitoes present in Hawaii were introduced by humans. Crucially, these introduced species have difficulty breeding at higher altitudes due to cooler temperatures. Therefore, mountainous areas and higher elevations in Hawaii are often less affected by mosquitoes. However, at sea level and in many resort areas, mosquitoes can be quite prevalent, especially during warmer, wetter periods. So, it's not entirely mosquito-free, but certain elevations offer refuge.

The Nuance of "Mosquito-Free"

It's important to understand that "mosquito-free" is a relative term. Even in the driest deserts, a small puddle after a rare rain shower can become a breeding ground for a specific type of mosquito. Similarly, in cold climates, the short summer can be an explosion of mosquito activity. The question of "which state doesn't have mosquitoes" is less about complete eradication and more about relative abundance and seasonal presence.

My own travel experiences underscore this point. In the desert Southwest, while walking near a riverbed or a small, persistent spring, I've encountered mosquitoes, albeit fewer and less aggressive than in humid regions. These are often species adapted to arid environments, capable of completing their life cycle rapidly when water becomes available.

Furthermore, human activity can inadvertently create mosquito habitats. Clogged gutters, discarded tires, birdbaths, and even small containers holding rainwater can become breeding sites in any state. This means that even in a predominantly arid or cold state, localized mosquito problems can still arise.

Factors Influencing Local Mosquito Abundance

Beyond the broad climate of a state, several local factors can significantly influence mosquito populations:

Water Management: The presence of reservoirs, irrigation systems, and drainage canals can create or eliminate breeding grounds. In agricultural areas, irrigation can lead to standing water that favors mosquitoes.
Urban vs. Rural: Urban areas can have mosquito problems due to artificial water-holding containers (e.g., flower pots, buckets, clogged drains). Rural areas, especially those with wetlands or agricultural fields, might have more natural breeding sites.
Elevation: Higher elevations are generally cooler, which can limit mosquito breeding and activity. This is why mountainous regions within states might have fewer mosquitoes than lower-lying, warmer areas.
Seasonal Variations: The timing and intensity of rainfall, as well as temperature fluctuations, play a huge role. A wet spring can lead to a significant mosquito season, while a dry spell can keep them at bay.

Debunking the Myth: No State is Truly Mosquito-Free

It's a common misconception that certain states are completely devoid of mosquitoes. The reality, based on scientific understanding and extensive field observations, is that every state in the contiguous United States has mosquitoes. The difference lies in the *density*, *species diversity*, and *seasonality* of these insects.

Let's consider a state like Wyoming, often perceived as wild and perhaps less populated. While its sparse population and vast open spaces might suggest fewer mosquitoes, it has numerous lakes, rivers, and wetlands, particularly in its mountainous regions and along its waterways. These provide ample breeding grounds during the warmer months. Similarly, states in the Pacific Northwest, while experiencing significant rainfall, also have cooler temperatures for much of the year which can temper mosquito activity compared to warmer, humid regions. Yet, during their warmer, wetter seasons, mosquitoes are certainly present.

My travels have taken me through parts of the Dakotas, known for their wide-open spaces. While not as humid as the Southeast, they have prairie potholes and agricultural areas that can retain water, creating seasonal breeding sites for mosquitoes.

Comparing Mosquito Prevalence Across States: A General Overview

To better understand the relative lack of mosquitoes, we can categorize states based on their general mosquito prevalence. This is a generalized view, and local conditions can always vary.

Category	States (Examples)	Reasoning
Lowest Prevalence (Primarily Due to Aridity/Cold)	Nevada, Arizona, New Mexico, Utah, parts of Wyoming, Montana, Idaho (especially higher elevations/drier regions)	Lack of consistent standing water, low humidity, and/or long, cold winters that limit breeding seasons.
Moderate Prevalence (Seasonal Activity)	Colorado, California (interior/northern), Oregon (interior/higher elevations), Washington (interior/higher elevations), North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas (western/northern), Idaho (lower elevations/wetter regions)	Mix of dry and wetter areas, distinct seasons with warm periods that allow for breeding, but not the pervasive humidity of the south. Cold winters limit year-round presence.
Highest Prevalence (Warm, Humid, Abundant Water)	Florida, Louisiana, Mississippi, Alabama, Georgia, South Carolina, North Carolina, parts of Texas, Arkansas, Tennessee, parts of Virginia, Delaware, Maryland, New Jersey, New York (coastal/southern), Connecticut, Rhode Island, Massachusetts, New Hampshire, Maine (coastal/southern), Michigan (southern), Wisconsin (southern), Minnesota (southern), Alaska (summer)	Consistent warmth, high humidity, abundant rainfall, and numerous natural water bodies (swamps, marshes, wetlands, lakes, slow-moving rivers) provide ideal breeding conditions year-round or for extended seasons.

This table offers a simplified view. For instance, California, a very large and geographically diverse state, has arid deserts in the south (low mosquitoes) and coastal wetlands in the north (higher mosquitoes). Similarly, while Alaska has intense summer mosquito seasons, its winters are virtually mosquito-free. Hawaii's issue is more about introduced species and their ability to thrive at lower altitudes.

Specific Case Studies: Exploring States Often Thought to Be Mosquito-Free

Let's dive deeper into some states that frequently come up in discussions about mosquito absence, and why the reality is more nuanced.

Alaska: The Land of Extremes

Alaska is a prime example of a state where the perception of mosquito-freeness clashes with reality. My cousin, a seasoned outdoorsman who lived in Alaska for years, always described summers there as a battle. He'd wear head nets, long sleeves, and heavy-duty repellent just to spend a few hours outside. While it's true that during the vast majority of the year, when temperatures are below freezing, mosquitoes are absent, the short summer months (roughly June through August) see an explosion of mosquito activity. This is due to the abundance of meltwater forming countless temporary ponds, lakes, and wetlands. The species present, like the Alaskan mosquito (*Aedes communis*), are incredibly robust and can survive harsh conditions, waiting for the brief window of opportunity.

The Arctic and subarctic regions, with their tundra ecosystems, are particularly notorious. The sheer numbers can be overwhelming, leading many to believe the state is infested. However, if your visit is during winter, then yes, you will find yourself in a mosquito-free state. The critical distinction is seasonality.

Hawaii: Tropical Paradise with a Caveat

Hawaii’s reputation as a tropical paradise might lead one to assume it’s teeming with mosquitoes. The reality is a bit more complex. The native Hawaiian Islands did not historically have mosquitoes. The mosquitoes present today were introduced, primarily *Aedes aegypti* and *Culex quinquefasciatus*. These species thrive in warm, humid, and often urban or semi-urban environments where containers can collect water. This means that coastal areas, valleys, and lower elevations, particularly in populated areas with gardens and irrigation, can experience significant mosquito populations.

However, the higher elevations of Hawaii's volcanic mountains are often significantly cooler, creating an environment less suitable for these introduced mosquito species. So, while you might need repellent for a luau on the beach, a hike in the misty, cooler highlands might offer a respite. The key here is elevation and specific microclimates, not the absence of mosquitoes across the entire state.

Arid Western States: Nevada, Arizona, Utah

These states are often cited as having low mosquito populations due to their desert climates. This is largely accurate. The extreme dryness and lack of consistent, large bodies of standing water are major limiting factors. However, it's not absolute. Following infrequent but sometimes heavy rainfall events, temporary pools can form, and certain hardy mosquito species can quickly exploit these opportunities. Areas near rivers, natural springs, or irrigated agricultural lands will almost always have some mosquito presence.

For example, while Las Vegas is in a desert, its extensive water features (pools, water parks, irrigation) and canals can create localized mosquito breeding sites. Similarly, in Arizona, the monsoon season can lead to a noticeable increase in mosquitoes as temporary puddles and washes fill with water. These mosquitoes are often short-lived but can be a nuisance during those periods. My own experiences in Arizona have shown that after a good rain, even in the desert, you might encounter a few buzzing around, especially at dawn and dusk.

The Role of Climate Change

It's worth noting that climate change is altering traditional patterns of insect distribution. Warmer winters in some northern states may allow mosquito species to survive and expand their ranges northward. Conversely, prolonged droughts in some traditionally humid regions might temporarily reduce mosquito populations. This dynamic factor means that the "mosquito map" of the United States could shift over time.

For example, states that previously had very short mosquito seasons due to cold might see longer periods of activity. This is a growing concern for public health as it expands the geographical range for mosquito-borne diseases.

Beyond Absence: Understanding Mosquito Behavior and Control

Even if a state has a generally lower mosquito population, understanding how to avoid bites is always wise. The question of "which state doesn't have mosquitoes" is, in many ways, a simplified framing of a more complex issue.

Tips for Minimizing Mosquito Bites (Regardless of State):

Even in areas with fewer mosquitoes, proactive measures can enhance your comfort and safety.

Use Repellent: Apply EPA-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone.
Wear Protective Clothing: Light-colored, loose-fitting, long-sleeved shirts and long pants can significantly reduce exposed skin.
Avoid Peak Mosquito Hours: Mosquitoes are typically most active at dawn and dusk. If possible, limit outdoor activities during these times.
Eliminate Standing Water: Regularly empty water-holding containers around your home, such as birdbaths, flower pots, and pet bowls.
Use Screens: Ensure window and door screens are intact and free of holes to prevent mosquitoes from entering your home.
Consider Mosquito Traps or Zappers: While their effectiveness varies, some people find these devices helpful in reducing local mosquito populations.

The effectiveness of these methods can be amplified by understanding local mosquito species and their behavior. For instance, some species are attracted to certain colors or scents, while others are more sensitive to air movement.

Frequently Asked Questions about Mosquito-Free States

Are there any states in the US that are completely mosquito-free?

No, there are no states in the United States that are completely mosquito-free. Every state, from the arid West to the humid South, and from the cold North to the tropical islands of Hawaii, has some presence of mosquitoes. The key differences lie in the abundance, species diversity, and seasonal activity of these insects. Some states have significantly fewer mosquitoes due to their climate (extreme dryness or cold), while others, particularly in the Southeast, have conditions that are ideal for mosquitoes year-round or for extended periods.

The perception of a state being "mosquito-free" is often a matter of relative experience. For instance, a visitor to the vast, dry desert regions of Nevada or Arizona during the hottest, driest part of the year might encounter very few mosquitoes. However, following rare rainfall events, even these arid areas can see a temporary surge in mosquito activity. Similarly, while Alaska is virtually mosquito-free during its long, harsh winters, its short summer months can be notoriously buggy due to abundant meltwater creating ideal breeding conditions.

Which states are known for having the fewest mosquitoes?

States known for having the fewest mosquitoes are generally those characterized by arid climates or extreme cold. These states have fewer natural breeding grounds (standing water) or their cold temperatures significantly limit the mosquito breeding season.

Arid States: Nevada, Arizona, New Mexico, and Utah are among the driest states in the US. Large portions of these states are desert, with limited rainfall and scarce permanent water bodies. This lack of consistent water severely restricts the ability of mosquitoes to complete their life cycles.
Cold States: Alaska experiences extremely cold winters, which kill off most adult mosquitoes and prevent breeding for a significant part of the year. However, its brief, intense summer can have very high mosquito populations. Other northern states with harsh winters, like Montana, Wyoming, and North Dakota, also tend to have shorter mosquito seasons compared to southern states.

It's crucial to remember that even in these states, localized mosquito populations can exist, especially near oases, rivers, irrigated agricultural lands, or in urban areas where artificial water-holding containers are present. The term "fewest mosquitoes" is comparative, not absolute.

Why do some states have so many more mosquitoes than others?

The primary reason for the vast difference in mosquito populations between states boils down to their habitat requirements. Mosquitoes require water for the aquatic stages of their life cycle (egg, larva, pupa). Therefore, states with abundant, consistent sources of standing water are prime breeding grounds. The Southeast, with its humid subtropical climate, extensive wetlands, swamps, marshes, and frequent rainfall, provides ideal conditions for mosquitoes year-round or for a significant portion of the year. States like Florida, Louisiana, Mississippi, and Alabama are prime examples.

Conversely, states with arid desert climates, such as those in the Southwest, have very little standing water for much of the year, naturally limiting mosquito populations. Similarly, states with long, intensely cold winters effectively reset mosquito populations annually, as freezing temperatures kill most adults and larvae, and prevent breeding for months. While these cold northern states might experience high mosquito activity during their short summers, their populations are generally less persistent and widespread than in the warmer, wetter southern states.

Other factors contributing to differences include:

Humidity: Higher humidity levels allow adult mosquitoes to survive longer.
Temperature: Mosquitoes are cold-blooded and their activity is temperature-dependent. Warmer temperatures generally mean more mosquito activity, up to a certain point.
Vegetation: Dense vegetation provides resting and harborage areas for adult mosquitoes.
Human Activity: Urban environments can create artificial breeding sites (e.g., discarded tires, clogged gutters, rain barrels).

What are the specific mosquito species found in the United States, and how do they differ?

The United States is home to over 170 species of mosquitoes, but only a few are of significant concern to humans as pests or disease vectors. These species have different preferences for breeding sites, feeding habits, and geographic distribution.

Some of the most common and impactful genera include:

Aedes: Often called "container breeders" or "floodwater mosquitoes." Many *Aedes* species lay eggs that can survive drying out for months and hatch when flooded. They are often aggressive biters, particularly during the day. Examples include:
- Aedes aegypti: The primary vector for Zika, dengue, and chikungunya. Prefers artificial containers around homes, is prevalent in the South.
- Aedes albopictus (Asian Tiger Mosquito): A highly adaptable and aggressive invasive species found in much of the eastern and southern US, and spreading. Also a vector for various diseases.
- Aedes vexans: A common nuisance mosquito found nationwide, often breeding in temporary floodwaters.
Culex: Often called "house mosquitoes." Many *Culex* species prefer stagnant, polluted water, such as ditches, clogged storm drains, and ponds. They are typically most active at dawn and dusk and are the primary vectors for West Nile virus in the US. Examples include:
- Culex pipiens: The Northern house mosquito, common in urban and suburban areas.
- Culex quinquefasciatus: The Southern house mosquito, prevalent in warmer climates.
Anopheles: Known as "malaria mosquitoes" (though malaria is rare in the US now). These mosquitoes breed in a wider variety of clean water habitats, including marshes, swamps, and rice fields. They are primarily active at night.
Culiseta: These are generally nuisance mosquitoes, often found in cooler climates and breeding in various types of standing water.

The distribution of these species is heavily influenced by climate. *Aedes aegypti* and *Culex quinquefasciatus* are more common in warmer, southern states, while *Aedes vexans* and *Culex pipiens* have a wider national distribution. *Anopheles* species are found in diverse habitats across the country. Understanding these differences is key to effective mosquito control and public health efforts.

Are there any islands or territories within the US that don't have mosquitoes?

The U.S. territories and states are not entirely mosquito-free. As mentioned, Hawaii has mosquitoes in its lower elevations, though higher altitudes are cooler. Puerto Rico and the U.S. Virgin Islands, being tropical, are known for significant mosquito populations and are vectors for diseases like Dengue and Zika. Guam and American Samoa also contend with mosquitoes. The U.S. has no permanently inhabited islands or territories that are naturally mosquito-free.

There are some extremely remote, high-altitude, or polar research stations in U.S. territories or interests where mosquitoes might be virtually absent for much of the year due to extreme cold or lack of breeding habitat. However, these are not states or typical inhabited regions. For example, research outposts in Antarctica might be mosquito-free, but Antarctica is not a U.S. state.

How does elevation affect mosquito populations in a state?

Elevation plays a significant role in determining mosquito populations within a state, primarily due to its impact on temperature and, consequently, the availability of suitable breeding and active periods. Mosquitoes are ectothermic (cold-blooded) insects, meaning their body temperature and activity levels are dictated by the ambient temperature. Higher elevations are generally cooler than lower elevations.

Here's how elevation impacts mosquito populations:

Reduced Breeding Success: Cooler water temperatures at higher elevations can slow down or halt the development of mosquito larvae and pupae. Some mosquito species have specific temperature thresholds for successful reproduction, and these may not be met in cooler mountain environments.
Shorter Activity Season: The warmer months are shorter at higher elevations. While lower elevations might experience mosquito activity for six to nine months of the year, higher altitudes might only have a suitable window for two to four months.
Limited Species Diversity: Many mosquito species are adapted to warmer climates. As elevation increases, the environment can become too cool for these species to thrive, leading to a reduced diversity of mosquitoes in mountainous regions compared to warmer, low-lying areas within the same state.
Less Humidity (Sometimes): While not always the case, higher elevations can sometimes be drier, further reducing conditions favorable for mosquito survival.

For example, in mountainous states like Colorado or California, the foothills and lower valleys might have a more robust mosquito population than the higher mountain ranges. In Hawaii, as discussed, the cooler, higher altitudes of the volcanic mountains are less hospitable to the introduced mosquito species found at sea level.

If I'm looking to minimize mosquito exposure for a vacation, which states should I consider?

If your primary goal is to minimize mosquito exposure, you should consider states in the arid Southwest or extremely cold northern states during their winter months. However, keep in mind the seasonal variations and potential for localized outbreaks.

States with predominantly arid climates and limited surface water are generally a good bet, especially during their dry seasons:

Nevada: Particularly the desert regions.
Arizona: Outside of monsoon season and areas near rivers or irrigation.
New Mexico: Similar to Arizona and Nevada.
Utah: Especially its desert basins.

For states with extreme cold, visiting during the winter months offers a virtually mosquito-free experience:

Alaska: From late autumn through early spring.
Montana, Wyoming, North Dakota, South Dakota, Idaho: During their long winters.

It is important to research the specific time of year and the particular region within a state you plan to visit. Even in the driest areas, a single rain event can temporarily increase mosquito numbers. Conversely, during the short summer in Alaska, mosquito populations can be extremely high.

Conclusion: The Ever-Present Mosquito

The search for a truly mosquito-free state in the U.S. is a quest that, unfortunately, leads to a null answer. Every state contends with these insects to some degree. The variations in mosquito populations are dictated by the fundamental requirements of their life cycle: water, temperature, and humidity. States that lack consistent standing water, such as the arid regions of the Southwest, or those that experience prolonged, freezing winters, like Alaska, will naturally have fewer mosquitoes for significant parts of the year. However, even these environments are not entirely immune. Temporary water sources can emerge after rains in the desert, and the brief, intense summers in Alaska can be a haven for bloodsuckers.

My personal travels, from the unexpectedly tranquil moments in the Montana wilderness to the buzzing evenings on a humid Southern porch, have reinforced this understanding. The absence of mosquitoes is a spectrum, not a binary state. For those seeking to minimize encounters, understanding the ecological factors that influence mosquito populations – their reliance on water and sensitivity to temperature – is key. By choosing destinations wisely, considering the time of year, and employing basic protective measures, you can significantly enhance your comfort and enjoy the diverse landscapes of the United States, even if a completely mosquito-free experience remains largely a myth.

Which State Doesn't Have Mosquitoes? Unpacking the Myth and Reality of Mosquito-Free Zones