Mosquito season in Sullivan County, MO: when it starts and ends
Mosquito months in Sullivan County
In a normal year mosquito season in Sullivan County, MO starts around April 14 and ends around October 22, about 27 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Sullivan County, and when
- Start tipping out standing water weekly by March 31.
- 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 Sullivan County are a nuisance; check window screens.
Sullivan County against the rest of MO
Sullivan County has the 113th longest season of 115 MO counties, at 191 days against 242 in Pemiscot County and 187 in Crawford County. Its mean temperature is 50.7°F.
- Scotland County: April 13 to October 22 (192 days, 0 WNV)
- Mercer County: April 14 to October 23 (192 days, 0 WNV)
- Worth County: April 14 to October 21 (190 days, 0 WNV)
- Crawford County: April 14 to October 18 (187 days, 0 WNV)
West Nile in Sullivan County
CDC ArboNET lists no human West Nile cases for Sullivan County from 1999 to 2025, though virus turned up in birds, mosquitoes or horses in 2 of those years.
Background: when mosquitoes go away for the winter; how the dates are worked out.