Weekly Update – August 24th – Few Mosquitoes for the Minnesota State Fair!
August 24, 2026
Mosquito numbers are low this week, which is typical for August and the lack of rain is contributing.
Mosquito numbers are not likely to get any higher this year. There are only a few weeks left of adult mosquito surveillance.
The temperatures may not feel like fall yet, but the mosquito season is definitely winding down. The end of August into early September is typically a low time of year for mosquito numbers and this year a statewide drought has kept mosquito numbers even lower than average.
Most of the floodwater and common human-biting mosquitoes are absent, but there are some unique species that tend to re-emerge or peak this time of year. MMCD Entomologist, Dr. Scott Larson, has one example: "Culiseta inornata is back after their summer hiatus. This chart (left) from 2020 shows their general pattern throughout a "normal' season. As they overwinter as adults they are an early season species, then the females apparently estivate (are dormant during summer), then are active again at the end of summer."
Culiseta inornata activity periods.
Uranotaenia sapphirina
Also, one of our favorite mosquitoes - Uranotaenia sapphirina - tends to be more active at the end of summer. According to Larson, "These are earthworm and leech biting mosquitoes that probably are the coolest looking mosquitoes we have in Minnesota because of their iridescent scales." (Photo above right.)
Here are this week's maps:
West Nile Virus Risk Has Ticked Up Slightly This Week
Several pools of mosquitoes tested positive for West Nile virus last week, elevating the vector index. We are still in the time of year when we see the typical peak transmission of West Nile virus, so while broader risk remains low, it's still important to avoid mosquito bites and monitor for any potential symptoms.
According to MMCD Vector Ecologist, Dr. Jordan Mandli, "eastern Hennepin County recorded some of the highest rates of WNV-positive mosquito pools. However, low overall mosquito abundance has limited the broader community risk."
Last week there were nine more positive samples of West Nile virus in our mosquito pools found in Anoka (1), Dakota (2), Hennepin (5), and Carver (1) Counties. This is the first positive sample for Carver County while the others have seen positive tests come back this year. Here is the current vector index:
Screenshot from a Beta version of the new Vector Index.
Back to School Time! MMCD Does School Presentations!
As the calendar switches over to September, we at MMCD get pumped for back to school because it means back to in-school presentations! Every year MMCD delivers over 40 presentations to elementary, middle, and high school students. If you know any teachers, please let them know about this FREE opportunity for students to learn more about mosquito and tick biology and how to protect themselves.
Learn more about our interactive classroom presentations on our Presentations webpage.
Presentations can be adapted for age, class size, and curriculum!
Upcoming Events - More Minnesota State Fair!
The Minnesota State Fair is underway and going strong! Come check out our booth in the Dairy Building where we will have live mosquito larvae, tick magnets to handout, educational displays, and helpful MMCD staff there to answer all your questions!
The State Fair is our only big event this week. Stay tuned next week for more!
Would you like MMCD to come to your event or speak to your group? E-mail Alex Carlson!
Video of the Week - MMCD School Presentations
A few years ago we put together this promo video to highlight MMCD school presentation offerings. We do interactive, station-based activities where students can get hands-on with mosquitoes and ticks and learn about how they affect public health and the ecosystem. We can even take things outside!
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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