First Mosquitoes Test Positive for West Nile Virus in 2026
June 25, 2026
Mosquito numbers are the highest they've been this year, but still below average.
Cattail mosquitoes bring overall numbers to the highest of 2026 so far, but still well below the 10-year average.
The "boring" mosquito season got some life last week when three things happened of note: 1) cattail mosquito emergence continued to push the weekly average up, 2) over an inch of rain fell in many areas prompting treatments, and crucially 3) the first mosquito samples tested positive for West Nile virus in 2026.
In terms of mosquito abundance, last week brought the highest weekly total of mosquitoes for 2026, though still below average. According to MMCD Entomologist, Dr. Scott Larson, "Cattail mosquitoes made up the majority of the mosquitoes in our adult surveillance network this week. Arguably, they will peak next week. The rain we received on Tuesday hatched a lot of Aedes vexans, so we can also expect those mosquitoes to increase in abundance in the short term." Typically the week of July 4th is our peak in mosquito abundance and it looks like that might be the case in 2026.
Despite some rain last week, the Twin Cities is still categorized as "abnormally dry" according to the drought monitor. Some rain may be in the forecast this week, so we will see if it is enough to add to the acres of mosquito breeding.
Here are this week's maps:
Mosquitoes Test Positive for West Nile virus in Four Counties
Last week we announced that the first mosquitoes had tested positive for West Nile virus in the Twin Cities in Hennepin, Ramsey, and Dakota Counties. Since then additional mosquitoes have tested positive for West Nile virus in Anoka County.
We are currently on schedule for when we typically expect to start seeing mosquitoes that test positive for West Nile virus. The disease has appeared every year since it first arrived in 2002. According to MMCD Vector Ecologist, Dr. Jordan Mandli, "Species composition continues to be dominated by Cx. restuans. The relatively low abundance of Culex spp. has likely helped slow the spread of the virus thus far. However, with temperatures expected to rise in the coming week, this situation could change."
The risk of West Nile virus increases as the summer progresses and we head into the warmer, latter months. 2025 was a record year of human West Nile virus cases in Minnesota, largely due to high abundance of Culex tarsalis mosquitoes. Currently, that species is behind this time last year, but late July is when the peak came in 2025 so it's still early.
We will include West Nile virus information in every weekly update from here to the end of the season. Please take precautions by applying EPA-registered insect repellent, wearing long sleeves, light colors, and loose fitting, and emptying out standing water.
MMCD in the News
With the announcement of our first West Nile virus detection, we had several local news stories that helped spread the word. Here are some examples:
- KARE 11 - Mosquitoes test positive for West Nile virus
- Star Tribune - Mosquitoes carrying West Nile virus found in three Twin Cities counties
- MPR News - Mosquitoes in Minnesota test positive for West Nile virus for the first time this summer
Upcoming Events
Come out and see staff from the Metropolitan Mosquito Control District at one of these upcoming events:
- Tuesday, June 30th - Ramsey Farmer's Market (Water Week) in Ramsey
- Saturday, July 4th - 4th of July Parade in Richfield
- Monday, July 6th - Woodbury Safety Camp in Woodbury
- Tuesday, July 7th - White Bear Lake Safety Camp in White Bear Lake
- Wednesday, July 8th - Nature at Nine at Harriet Alexander Nature Center in Roseville
- Wednesday, July 8th - Coon Rapids Farmers Market in Coon Rapids
Would you like MMCD to come to your event or speak to your group? E-mail Alex Carlson!
Video of the Week - National Mosquito Control Awareness Week Highlights
For National Mosquito Control Awareness Week, Public Affairs Assistant Kylie Rich-Vetsch put together a series of videos covering the different aspects of Integrated Pest Management. These include close looks at Surveillance, Identification, Control, and Review.
Win an MMCD T-Shirt!
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