Mosquito season in Wapello County, IA: when it starts and ends

Mosquito months in Wapello County

In a normal year mosquito season in Wapello County, IA starts around April 13 and ends around October 22, about 27 weeks.

1. Jan
2. Feb
3. Mar
4. Apr
5. May
6. Jun
7. Jul
8. Aug
9. Sep
10. Oct
11. Nov
12. Dec

What to do in Wapello County, and when

• Start tipping out standing water weekly by March 30.
• Book any yard treatment for mid April, ahead of the July peak.
• Repellent can go away after October 22.
• No West Nile cases since 2016, so bites in Wapello County are a nuisance; check window screens.

Wapello County against the rest of IA

Wapello County has the 5th longest season of 99 IA counties, at 192 days against 198 in Des Moines County and 160 in Worth County. Its mean temperature is 50.7°F.

• Davis County: April 12 to October 24 (195 days, 0 WNV)
• Fremont County: April 13 to October 23 (193 days, 1 WNV)
• Johnson County: April 13 to October 21 (191 days, 7 WNV)
• Mills County: April 13 to October 21 (191 days, 3 WNV)

West Nile in Wapello County

From 1999 to 2025, CDC ArboNET counted 4 human West Nile cases in Wapello County (2 neuroinvasive) across 3 years. The worst was 2006 with 2; the latest was 2007.

Background: when mosquitoes go away for the winter; how the dates are worked out.