How MMCD Monitors and Treats Catch Basin to Reduce Mosquito-Borne Disease
August 28, 2023
New Video – MMCD Offers Free Tire Recycling for District Residents; Learn What You Need to Qualify
September 11, 2023
The MMCD booth at the Minnesota State Fair was a hit! The Kids Table brought in lots of creative visitors.
The last week in August continues the trend of low annoyance mosquitoes, high West Nile vectors.
Every Monday night starting in mid-May through September, the Metropolitan Mosquito Control District sets out a variety of mosquito and black fly traps throughout the district and employs a network of sweep net collections done by employees and volunteers. Any insects collected are brought back to our lab on Tuesday to be identified throughout the week with maps published to show current mosquito and black fly activity.
The dry weather continues in Minnesota and that combined with the cooling weather and the changing of the seasons means that mosquitoes are on the continual decline from what had already been a below average year. Based on sampling from Monday, August 28th only 13 CO2 traps collected more than 50 human-biting mosquitoes and throughout the District mosquito numbers are below average - though August is a typically low month for mosquitoes. However, Culex mosquitoes, our region's primary vector for West Nile virus, are still high.
According to MMCD assistant entomologist Dr. Scott Larson, "Again, very few mosquitoes and the problem ones are the Culex. Some of the gravid traps collected lots and lots of them. Too many, even."
Here are the mosquito trap counts from last Monday, August 28th:
Mosquitoes continue to test positive for West Nile virus, though cool weather slowed them down a bit.
More mosquitoes collected have tested positive for West Nile virus over the past few weeks, however, cooler weather has led to a drop in positive samples. According to MMCD Vector Ecologist Kirk Johnson on Friday, "For the past five weeks it has been over 10/1000 mosquitoes tested and as high as 15.9/1000. The infection rate for mosquitoes tested this week stands at 5.9/1000. This is the result of cooler weather from two weeks ago when there were several days with highs in the 70’s and lows in the upper 50’s."
It is common to see a surge in Culex mosquitoes in the Fall, even in dry years because this species is less impacted by drought conditions and thrives in man-made habitats like waste tires and catch basins. However, this year there has been more positive West Nile virus tests than the past several years.
This is a good reminder that even when nuisance mosquitoes seem to be low, it's important to take precautions to avoid mosquito bites. Wear insect repellent and cover up during peak mosquito activity periods.
