Mosquitoes in Iowa

Iowa is home to roughly 56 mosquito species, and the vast majority are simply an outdoor nuisance. A small number, however, are capable of carrying West Nile virus — which is why standing water and timing matter more with mosquitoes than with most other backyard pests.

Common Breeding Sites Around Your Yard

Old tires, buckets, and containers holding rainwater

Clogged gutters and downspouts

Bird baths and pet water bowls left unchanged

Unused kiddie pools or any standing water left over a week

Mosquitoes can lay eggs in containers as small as a bottle cap — it doesn't take much standing water to matter.

When Are Mosquitoes Most Active?

By season

MayJunJulAugSepOct

Active season Peak activity (Jun–Aug)

By time of day

6am9am12pm3pm6pm9pm

Low activity Peak biting (dusk & dawn)

West Nile Virus Risk

West Nile virus is spread primarily by Culex mosquitoes, which pick up the virus from birds and can then transmit it to people. Most mosquitoes in Iowa don't carry it, but the risk is real enough that the state actively monitors populations every season.

Most people (about 4 in 5)

No symptoms at all, or mild flu-like symptoms — fever, headache, body aches, joint pain — that resolve on their own.

About 1 in 150

Develop severe illness affecting the nervous system. Older adults and those with weakened immune systems face the greatest risk of this outcome.

Reducing Mosquitoes Around Your Home

1. Empty or remove standing water weekly — containers, gutters, bird baths, and pet bowls

2. Keep window and door screens in good repair

3. Use an EPA-registered repellent when spending time outdoors at dusk or dawn

4. Wear long sleeves and pants during peak biting hours when practical

Your Questions About Mosquitoes Answered

Do all mosquitoes in Iowa carry West Nile virus?

No. Iowa has around 56 mosquito species, and only Culex mosquitoes are considered effective carriers of West Nile virus. Most species detected in the state aren't capable of transmitting it even if exposed.

Why do I have so many mosquitoes after it rains?

Standing water from rain or flooding is prime mosquito breeding habitat. Heavier rainfall years have been directly linked to population surges in Iowa, since more standing water means more places for eggs to develop.

When does mosquito season end in Iowa?

Activity typically tapers through September and drops sharply once nighttime temperatures fall below 50°F, with the first hard frost generally ending the season for the year.

Is it worth avoiding the outdoors at dusk and dawn?

If you're in a high-mosquito area, yes — that's when most species, including Culex, are most active. It's a simple way to meaningfully cut down on bites without changing much else about your routine.

How does professional mosquito control work?

Treatment typically targets standing water and breeding sites on the property directly, often alongside barrier treatments in vegetation where adult mosquitoes rest during the day.

Dealing with a mosquito problem?

Reach out and we'll help you figure out what's going on.