Texas and Florida top the list of states with the most mosquitoes, hosting 85 and 80 species respectively. Both states combine warm climates, long wet seasons, and vast stretches of standing water habitat that let mosquito populations thrive from late winter through fall. But the full picture is more nuanced than a simple ranking, because “most mosquitoes” can mean the greatest species diversity, the highest raw population numbers, or the worst impact on daily life.
Top States by Mosquito Species Count
The number of mosquito species present in a state is one of the clearest measures of overall mosquito burden. States with more species tend to have diverse habitats (swamps, forests, coastline, urban areas) that support different breeding strategies. Here’s how the top states stack up:
- Texas: 85 species. Season runs February through November in the south, March through September in the north.
- Florida: 80 species. Same extended season as Texas, with some areas active year-round.
- New York: 70 species. Active from late April through September.
- Louisiana: 68 species. Season mirrors the Gulf Coast pattern, February through November in southern parishes.
- Georgia: 63 species. March through September.
- South Carolina: 61 species. March through September.
- Alabama, Kentucky, New Jersey, North Carolina, Oklahoma, Pennsylvania: Each hosts around 60 species.
A clear pattern emerges: southeastern and Gulf Coast states dominate. Their combination of heat, humidity, rainfall, and abundant wetlands creates ideal conditions. But a few surprises appear on the list. New York ranks third in species diversity thanks to its mix of coastal marshes, urban water features, and forested wetlands stretching from Long Island to the Adirondacks. New Jersey and Pennsylvania also crack the top tier, a reminder that mosquito problems aren’t limited to the Deep South.
Alaska: A Special Case in Sheer Numbers
Alaska hosts only 27 mosquito species, a fraction of what Texas or Florida support. But in raw population size, it may be the most mosquito-dense place in the country. Derek Sikes, curator of insects at the University of Alaska Museum of the North, once calculated that roughly 17 trillion mosquitoes hover over Alaska each summer, with a combined weight of about 96 million pounds.
The reason is habitat. Alaska’s vast swamplands, bogs, and tundra pools create an enormous network of standing water during snowmelt season. Female mosquitoes lay eggs in the fall, placing them on water surfaces or on ground that will flood when snow melts the following spring. The larvae develop in those shallow pools by the billions. One species, the “snow mosquito,” hibernates on the forest floor through winter and emerges as soon as the ground warms. These are smaller and quieter than the mosquitoes most Americans encounter, but they bite aggressively and swarm in densities that can make parts of the state nearly unbearable in June and July.
Worst Cities for Mosquito Activity
Orkin’s 2025 ranking of top mosquito cities, based on the number of new residential mosquito treatments performed between April 2024 and March 2025, offers a different lens. It measures where people are actually calling for help, which reflects both mosquito pressure and population density. Los Angeles claimed the number one spot for the fourth consecutive year, followed by Chicago, New York, Atlanta, and Detroit.
Several cities made surprising jumps. Detroit entered the top five for the first time. Cleveland leaped 10 spots to number nine, and Denver climbed six spots into the top 10. These shifts suggest mosquito problems are intensifying in the Midwest and Mountain West, not just traditional hotspots along the Gulf Coast. Meanwhile, cities you might expect near the top, like New Orleans and Miami, ranked 50th and 12th respectively. That gap likely reflects differences in how aggressively residents use professional pest control rather than actual mosquito abundance.
The full top 10: Los Angeles, Chicago, New York, Atlanta, Detroit, Houston, Dallas, Washington D.C., Cleveland, and Denver.
When Mosquito Season Peaks by Region
Mosquito season length varies dramatically depending on where you live. Gulf Coast states, Florida, and Hawaii have the longest seasons, with activity starting as early as February and lasting through November. In some southern Florida and Hawaiian locations, mosquitoes are active year-round.
Southern and inland southwestern states typically start seeing mosquitoes in March, with peak activity running May through September. The Mid-Atlantic, Great Lakes, and northern West see seasons begin in April, with rain and summer heat driving surges in June through August. New England, the northern Midwest, and the Pacific Northwest have the shortest seasons, generally May through September, with cool nights slowing activity on either end.
Across most of the country, July and August are the peak months. That’s when heat and rainfall align to maximize breeding. Higher-elevation areas in the interior West start even later, often not seeing significant mosquito activity until June.
Disease Risk Varies by State
More mosquitoes doesn’t always mean more disease, but the two are connected. West Nile virus is the most common mosquito-borne illness in the U.S., and its geographic distribution is uneven. In 2024, as of mid-August, the CDC recorded 222 human cases across 32 states, with at least eight deaths. Arizona led with 76 cases, followed by Texas with 31 and California with 29. Alaska and Hawaii reported zero cases, and 18 states total had none.
The primary carrier of West Nile is a type of mosquito in the Culex genus, which picks up the virus from infected birds and passes it to humans. These mosquitoes breed readily in polluted standing water, including storm drains, neglected pools, and even puddles contaminated with leaf debris. A separate group, the Asian tiger mosquito, has spread across much of the eastern U.S. after arriving from Asia. It breeds in small containers like discarded tires, flowerpots, and pet water dishes, and it bites aggressively during the daytime, unlike most native species that feed at dawn and dusk.
What Drives Mosquito Populations
Three factors determine how bad mosquitoes get in any given state: water, heat, and time. Mosquitoes spend their larval stage entirely in water, so any state with abundant standing water, whether natural wetlands, rice paddies, drainage ditches, or just millions of backyard containers, will support larger populations. Heat speeds up their development cycle. In warm Gulf states, mosquitoes can go from egg to biting adult in under a week, allowing multiple generations to stack up over a long season. And season length matters enormously. A state like Florida, with nine or ten months of mosquito-friendly weather, produces far more total mosquitoes than Minnesota, even if both states have plenty of suitable water habitat.
Urban areas add their own wrinkle. Cities generate heat islands that extend mosquito seasons and provide endless small water sources: clogged gutters, construction sites, tire piles, forgotten buckets. That helps explain why cities like Los Angeles and Chicago rank so high for mosquito treatments despite not being in traditionally swampy territory.
Reducing Mosquitoes Around Your Home
Public mosquito control programs in high-burden states use a layered approach. They start with source reduction, eliminating standing water where mosquitoes breed. They treat water that can’t be drained with biological larvicides, bacterial products that kill mosquito larvae without harming other wildlife. And they use targeted insecticide applications against adult mosquitoes during peak activity periods.
At the household level, the most effective step is eliminating standing water on your property. Empty pet water dishes and birdbaths at least once a week. Store unused tires under cover or cut them in half so they can’t collect rainwater. Clean gutters regularly. Screen rain barrels and cisterns. Even a bottle cap full of water can support mosquito larvae in warm weather, so annual yard cleanups that remove containers, old pots, and debris make a real difference. Community clean-up campaigns have been shown to significantly reduce populations of the Asian tiger mosquito, which breeds almost exclusively in small artificial containers close to homes.