Mosquito season in Bartholomew County, IN: when it starts and ends
Mosquito months in Bartholomew County
In a normal year mosquito season in Bartholomew County, IN starts around April 4 and ends around October 30, about 30 weeks.
- Jan
- Feb
- Mar
- Apr
- May
- Jun
- Jul
- Aug
- Sep
- Oct
- Nov
- Dec
What to do in Bartholomew County, and when
- Start tipping out standing water weekly by March 21.
- Book any yard treatment for early April, ahead of the July peak.
- Repellent can go away after October 30.
- 4 West Nile cases since 2016 (last 2025): you should use repellent at dusk June to August, more so if over 60.
Bartholomew County against the rest of IN
Bartholomew County has the 22nd longest season of 92 IN counties, at 209 days against 231 in Floyd County and 177 in Steuben County. Its mean temperature is 54°F.
- Harrison County: April 6 to November 2 (210 days, 0 WNV)
- Clay County: April 3 to October 29 (209 days, 1 WNV)
- Scott County: April 5 to October 31 (209 days, 0 WNV)
- Decatur County: April 5 to October 29 (207 days, 0 WNV)
West Nile in Bartholomew County
From 1999 to 2025, CDC ArboNET counted 7 human West Nile cases in Bartholomew County (6 neuroinvasive) across 6 years. The worst was 2025 with 2; the latest was 2025.
See how the dates are worked out, and reading the West Nile counts.