Weekly Update – August 31st – Unsurprisingly Low Mosquito Counts
August 31, 2026
Weekly Update – September 15th – Preparing for 2027
September 15, 2026
There is no indication that mosquito numbers are going anywhere but down for the rest of the year.
The September Slow-Down for Mosquitoes is Upon Us.
The State Fair is over, all schools are now back in session, and the mosquito numbers are very low - all of these are signs that we have passed Labor Day and are now entering the heart of September.
From here on out we watch temperatures to determine if our Monday night mosquito surveillance will continue. According to District Entomologist, Dr. Scott Larson, "As soon as the temperature at dusk is predicted to be below 55 degrees Fahrenheit we will stop with the CO2 trapping and sweep net sampling. Will the temperatures drop before the week of September 21st? In the last 20 years, we have only run traps that week (the 38th week of the year) just one third of the time."
According to the extended forecast, there are a couple of days ahead with highs in the 60s and lows in the 50s, but it's unclear if it will stay that way or rebound for a few more weeks of heat. This weekly update is coming a day later than usual and traps and sweep net collections occurred last night, so there will be at least one more Weekly Update before we recap the season and take a break.
Here are this week's maps:
West Nile Virus Risk Also on the Down Swing
Nationally, August is the peak month for the onset of West Nile virus and September is in 2nd place. However, in Minnesota there aren't likely to be as many WNV cases in September due to cooler temperatures, shorter days, and the winding down of the mosquito season in general.
Last week there were five more positive samples of West Nile virus in our mosquito pools found in Hennepin (2) and Ramsey (3) Counties. According to MMCD Vector Ecologist, Dr. Jordan Mandli, "Despite this decrease in activity, we continue to monitor these areas closely because of their higher human population density and the potential for increased human exposure." Here is the current vector index:
Screenshot from a Beta version of the new Vector Index.
Mosquitoes are Almost Gone, but Ticks are Coming Back!
As we turn the page into fall, most insects enter diapause and begin to cease activity in preparation for cold winter months. Ticks (which are arachnids, not insects) are another story, however. In September and October adult deer ticks re-emerge and begin seeking a blood meal that they will use to produce eggs in the coming spring.
We've had a hot summer (the 6th hottest on record) and long-term forecasts suggest we could be in for another warmer than usual fall and winter. Ticks will be out questing any time temperatures are consistently above freezing, so be on the lookout when you are out on fall hikes or going hunting.
Deer tick activity month-to-month.
Upcoming Events
We had a great time at the Minnesota State Fair and had thousands of people visit our booth in the Dairy Building. The Fair might be behind us, but event season isn't over! We've got a busy week ahead so come out and see staff from the Metropolitan Mosquito Control District at one of these upcoming events:
- Friday, September 11th- Bark in the Park in Corcoran
- Saturday, September 12th - Monarch Festival in Minneapolis
- Saturday, September 12th - Osseo Lions Roar Parade in Osseo
- Sunday, September 13th - Open Streets in Minneapolis
Would you like MMCD to come to your event or speak to your group? E-mail Alex Carlson!
Video of the Week - Meet the Fleet: Bell Helicopter - Mosquito Control
The Metropolitan Airports Commission recently featured the helicopters that do larval control for MMCD on their "Meet the Fleet" video series. Scott Churchill who owns the helicopters and Casey Herrmann from MMCD do a great job of explaining how helicopters do their important work.
Win an MMCD T-Shirt!
Here is your chance to win either the new MMCD Attack Larvae T-Shirt or last year's Laser Loon shirt. Sign up for "The Weekly Buzz" newsletter with Weekly Mosquito updates. Each week there will be a trivia question at the end. Two correct answers each week will get a shirt!
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