Today's Mosquito Risk in Iowa: Real-Time Forecast & Activity Map
Check your ZIP code for local mosquito activity, West Nile risk, and prevention insights.
Built from CDC and NOAA data
Mosquito Surveillance Insights
- Annual WNV Cases
- about 20 to 40 confirmed cases annually
- Based on CDC ArboNET surveillance data
- Risk Tier
- Tier 3: Moderate
- Western Iowa shares the Plains Cx. tarsalis pattern; eastern Iowa mirrors Illinois.
- Per mosquito-risk-model regional tier
- Highest-Risk Areas
- Polk, Linn, Scott, Woodbury (WNV); western agricultural counties (Cx. tarsalis)
Current Situation in Iowa
Iowa carries a moderate WNV burden of roughly 20 to 40 confirmed human cases annually, distributed across the Des Moines, Cedar Rapids, Davenport, and Sioux City metros. Western Iowa shares the Plains Cx. tarsalis pattern, with irrigated cropland and prairie pothole wetlands sustaining the agricultural Culex that drives WNV transmission across rural counties. Eastern Iowa mirrors the Illinois pattern, with Cx. pipiens dominating urban Des Moines and Cedar Rapids transmission. Aedes albopictus is limited and mostly restricted to the southeast corner. EEE is rare. The prairie pothole wetlands across the north central counties produce big spring Aedes vexans hatches off snowmelt. The Mississippi and Missouri River bottomlands hold steady summer populations. The Loess Hills along the western border hold seasonal woodland Aedes. Biting season runs June through September.
Snapshot of the current mosquito situation in Iowa, drawn from CDC ArboNET surveillance and the regional risk model.
- Risk Level
- Moderate
- Peak Activity
- June through September
- Dominant Vector
- Northern House Mosquito (Culex pipiens); Western Encephalitis Mosquito (Culex tarsalis) western half
Where Mosquitoes Breed in Iowa
Iowa mosquito habitat is built on prairie pothole wetlands, the Mississippi and Missouri River bottomlands, and the agricultural drainage grid. The prairie pothole region across the north central counties from Algona through Mason City produces big Aedes vexans hatches after spring snowmelt, with the Iowa Great Lakes around Spirit Lake and Okoboji as a focal habitat. The Mississippi River bottomlands from Davenport through Dubuque and the Missouri River floodplain at Council Bluffs and Sioux City sustain summer Cx. pipiens and Aedes vexans populations, with De Soto National Wildlife Refuge as a key producer. Western Iowa irrigation canals and the Big Sioux River corridor hold dense Cx. tarsalis populations through summer. The Loess Hills along the Missouri River and Effigy Mounds along the Mississippi hold woodland Aedes off forested wetlands. Storm drains and tire piles across Des Moines, Cedar Rapids, Davenport, and Sioux City carry the urban Cx. pipiens load.
Hotspot Counties & Areas
- Polk County (Des Moines metro)
- Linn County (Cedar Rapids)
- Scott County (Davenport, Mississippi River)
- Woodbury County (Sioux City, Missouri River)
- Iowa Great Lakes (Dickinson County, Spirit Lake)
- De Soto National Wildlife Refuge
- Loess Hills (Harrison and Pottawattamie counties)
- Effigy Mounds (Allamakee County, Mississippi bluffs)
Seasonal Activity Pattern
Biting starts in early to mid June after snowmelt drives the first floodwater Aedes hatch, peaks in late July through August, and tapers through September. WNV cases concentrate in August across the Des Moines and Cedar Rapids metros and the western agricultural counties. The prairie pothole region produces the heaviest spring Aedes vexans pulse from late May through June. Western Iowa Cx. tarsalis populations stay elevated from June through September with the irrigation cycle, mirroring the Plains pattern. Aedes albopictus daytime biting in the southeast corner runs from July through September. Heavy summer storms produce floodwater Aedes pulses along the Mississippi, Missouri, and Big Sioux bottomlands.
Monthly Biting Intensity (Midwest)
Iowa Mosquito Risk Profile
- WNV burden level
- Moderate
- about 20 to 40 confirmed cases annually
- EEE risk
- Rare
- Peak biting season
- June through September
- Top urban risk areas
- Des Moines (Polk)
- Cedar Rapids (Linn)
- Davenport (Scott)
- Sioux City (Woodbury)
Signature habitat: prairie potholes, Mississippi and Missouri River bottoms, agricultural drainage ditches.
Climate driver: Western Iowa shares the Plains Cx. tarsalis pattern; eastern Iowa mirrors Illinois.
Check Your Local Mosquito Risk
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Common Mosquitoes in Iowa
Understanding which mosquitoes are active in Iowa helps you identify threats and take appropriate precautions. Click any card for details.
Northern House Mosquito
Culex pipiens
Risk: West Nile virus, St. Louis encephalitis, dog heartworm.
Key feature: Medium brown body with banded abdomen. Looks nearly identical to Cx. quinquefasciatus.
Active: Late spring through early fall in the north. Adult females overwinter in basements, garages, and storm drains.
Inland Floodwater Mosquito
Aedes vexans
Risk: Aggressive nuisance biter. Weak vector for West Nile, dog heartworm.
Key feature: Brown body with pale bands on the legs and a tapered abdomen.
Active: Spring through fall. Population spikes a week or two after major rain events.
West Nile Virus
Vector: Northern House Mosquito
West Nile Virus
The dominant West Nile vector across the northern half of the US. About 80% of infections are asymptomatic.
What to watch for
- Onset typically 2 to 15 days after a bite
- Most cases mild or asymptomatic, small fraction severe
- Neurological signs (severe headache, neck stiffness, confusion) need ER care
Breaking the Cycle in Iowa
The mosquito lifecycle takes about a week. These habits cut local biting pressure faster than anything else, building multiple layers of protection.
Drain the Yard Weekly
Empty buckets, planter saucers, kiddie pools, tarps, and clogged gutters. A week of standing water is one full mosquito generation.
Repel Before Going Out
EPA-registered DEET (20-30%), picaridin (20%), IR3535, or oil of lemon eucalyptus. Apply before going outside, especially at dusk and dawn.
Seal the House
Window and door screens with no tears. AC and porch fans both work. Mosquitoes struggle to fly upwind even at 1-2 mph air speed.
Treat Outdoor Clothing
Permethrin-treated long sleeves and pants for evening yard work, hiking, or fishing. Remains effective through 70+ wash cycles.
If You Develop Symptoms
Most mosquito bites are harmless. A small fraction can transmit illness, and knowing the timeline matters more than panicking at every itch.Five things to know.
Watch for fever
Fever, body aches, headache, or fatigue 2 to 15 days after a bite. West Nile often feels like flu, and most infections never get diagnosed.
Note where and when
A rough record of where and when you got bitten helps your doctor decide what to test for. Date, location, mosquito-heavy areas you visited.
Get help fast for neuro signs
Severe headache, neck stiffness, confusion, vision changes, or sudden muscle weakness can mean neuroinvasive WNV or EEE. Both are medical emergencies.
Pregnant exposure?
If pregnant and bitten in an area with documented Zika or local dengue transmission, mention to your OB. Same goes for travel exposure.
Children and seniors
Higher risk of severe disease from WNV, EEE, and dengue in adults over 60 and children under 5. Early call to the pediatrician or PCP if symptoms appear.
When does mosquito season end in Iowa?
Mosquito activity winds down after the first hard freeze, which in Iowa typically arrives around Oct 10. See the local first-frost window and city-by-city freeze dates.
Iowa first frost datesAlso worried about ticks in Iowa?
Lyme disease risk and tick activity track different seasonal patterns than mosquitoes. See your Iowa tick forecast.
View Iowa tick forecastStay Safe in Iowa
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