Mosquito season in DeKalb County, MO: when it starts and ends

Mosquito months in DeKalb County

In a normal year mosquito season in DeKalb County, MO starts around April 11 and ends around October 24, about 28 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 DeKalb County, and when

• Start tipping out standing water weekly by March 28.
• Book any yard treatment for mid April, ahead of the July peak.
• Repellent can go away after October 24.
• No West Nile cases since 2016, so bites in DeKalb County are a nuisance; check window screens.

DeKalb County against the rest of MO

DeKalb County has the 103rd longest season of 115 MO counties, at 196 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 51.7°F.

• Harrison County: April 10 to October 25 (197 days, 1 WNV)
• Clark County: April 11 to October 24 (196 days, 0 WNV)
• Nodaway County: April 11 to October 23 (195 days, 0 WNV)
• Adair County: April 12 to October 24 (195 days, 0 WNV)

West Nile in DeKalb County

CDC ArboNET lists no human West Nile cases for DeKalb County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 4 of those years.

More: how the dates are worked out · when the season starts across the US.