Weekly Update – July 25th – Looking Like 2021 All Over Again
August 2, 2022
Weekly Update – August 8th – At Least One More Week with Few Mosquitoes
August 15, 2022
Nuisance mosquito numbers remained low in last week's collections.
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.
Through the beginning of last week there was not much rain in the District, which led to a continued decline in the number of human-biting mosquitoes collected in CO2 traps on Monday, August 1st.
According to MMCD assistant entomologist, Dr. Scott Larson, "only a single CO2 trap captured over 130 adult mosquitoes this week." While it is pretty rare that traps would collect this few mosquitoes, we are entering a time of year when the overall number of mosquitoes tends to decline as demonstrated in the 10-year average line in the graph above. August is a month when nuisance mosquitoes tend to decline while disease-carrying and container breeding mosquitoes are plentiful.
Here are the mosquito trap counts from last Monday, August 1st:
Mosquitoes test positive for West Nile virus in Anoka, Dakota, Hennepin, and Ramsey Counties.
Last week we saw the total number of samples that have tested positive for West Nile virus this year almost double. According to MMCD Vector Ecologist Kirk Johnson, "Six of 51 mosquito samples tested [last week] were positive for WNV. All of the positive samples were from this week’s gravid trap surveillance." All of the counties where positive samples were collected have already had positive results at other times this year. This just underscores that the West Nile virus threat is active and residents in those counties should take precautions by applying insect repellant, wearing long sleeves and light colors, and avoiding the peak feeding times of dawn and dusk.
Weekend rainfall could change the mosquito outlook for August.
Over the weekend of August 5th through 7th, most of the District saw over an inch of rain. This precipitation was long overdue in an area that was entering drought status and will likely change the mosquito outlook for the last full month of summer. The story of 2022 thus far has been few nuisance mosquitoes because of limited rain and increasing West Nile virus activity because of hot temperatures. Now that there have been several days of heavy rain and slightly cooler temperatures, it could mean the situation changes.
MMCD technicians are active in communities today trying to find the sites that are breeding mosquitoes and helicopters will likely be out tomorrow and Wednesday conducting treatments. Find out about the latest surveillance and treatment activity on our Planned Treatments webpage.
Check back over the next several weeks to learn what impact the rain had on mosquito activity.
For the latest updates on mosquito control, disease activity, and planned treatments, follow MMCD on Twitter or Facebook.
