Weekly Update – August 10th – Mosquito Numbers Back to Early Spring Levels
August 10, 2026
Mosquito numbers are low this week, but they're almost always low at this time of year.
Mosquito numbers were low again this week, but now they are at least in line with what we expect this time of year.
Overall mosquito numbers were actually the closest to average they have been all year in last week's trap collections. That's because in mid-August, the number of mosquitoes is historically low as the end of summer usually brings less rain and the early season spring Aedes and cattail mosquitoes have mostly died off at this point. According to the drought monitor, almost all of the Twin Cities are now under severe or moderate drought conditions.
At this point in the year even a good soaking of rain is not likely to hatch that many mosquitoes as we approach the season when the sun sets early and many species prepare to enter diapause. Last week, MMCD treated 10,210 acres of wetlands as a pre-hatch method, targeting areas where larvae may emerge the next time it rains. This makes it so we are prepared when it does rain and will need to allocate fewer resources to preventing a significant mosquito brood. This was the last pre-hatch treatment of 2026 and will likely be the last time helicopters are used until late Fall when cattail treatments occur.
It's starting to feel like Fall! Here are this week's maps:
West Nile Virus Risk Remains Low Heading Into the State Fair
Not only have overall mosquito numbers been low this year, but August vector species numbers have been low as well. That's not always the case in drought years as the species responsible for West Nile virus transmission often uses catch basins and other urban areas that aren't as impacted by dry weather.
According to MMCD Vector Ecologist, Dr. Jordan Mandli, "While Cx. restuans and Cx. pipiens continue to make up the majority of our positive mosquito pools, Cx. tarsalis made an unexpected return to pool representation this past week. Some regions are also experiencing elevated vector indices, indicating that localized areas of concern remain."
Last week there were five more positive samples of West Nile virus in our mosquito pools found in Anoka (1), Dakota (1), Ramsey (1), and Hennepin (2) Counties. Each of these counties has had a positive sample already this year. Here is the current vector index:
Screenshot from a Beta version of the new Vector Index.
Deer Ticks on the Decline?
Last week's trivia question in the Weekly Buzz (available only to people who subscribe to the free weekly newsletter) stumped quite a few people. The question was "Which of these does NOT happen in August?" and the options were A) The highest month for West Nile virus transmission, B) The start of the Minnesota State Fair, C) Deer tick numbers decline in Minnesota, or D) The MMCD adult mosquito surveillance network concludes. Most people chose D for the answer, but it is actually C) Deer tick numbers decline in Minnesota.
If you refer to our Tick Surveillance webpage, you will see two graphs of activity periods that show that both nymphal deer tick and adult deer tick numbers decline in August. For adult blacklegged ticks, their numbers will tick back up in late September into October, but August is typically one of the quieter summer months for Deer tick activity.
There's a reason that I always schedule my camping trips for August! For the record, the MMCD adult mosquito surveillance network will continue into at least mid-September.
Staff from our Maple Grove facility out checking for mosquito larvae.
Upcoming Events - Minnesota State Fair Week
The Minnesota State Fair starts Thursday and MMCD will be there again this year! 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!
It's not just the Fair happening! Here are the other events going on this week:
- Wednesday, August 26th - Brooklyn Park Safety Camp in Brooklyn Park
- Thursday, August 27th - Monday, September 8th - Minnesota State Fair in St. Paul
- Thursday, August 27th - Concert in the Park in Shorewood
- Sunday, August 30th - Woodbury Days Parade in Woodbury
Would you like MMCD to come to your event or speak to your group? E-mail Alex Carlson!
Video of the Week - Mosquito Basketball Challenge
"Ain't no rule that says a mosquito can't play basketball." Our latest video sets up the MMCD All-Stars in a match-up versus a giant mosquito. The All-Stars seem cooked until coach unveils the secret weapon that EVERYBODY should be using!
Thanks to Tyler Davis, Rayjon Teachout, Brandon Dusterhoft, Kylie Rich-Vetsch, and Matt Foss (as the mosquito) for help with this video!
Check it out below:
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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