Weekly Update – August 1st – Nuisance Mosquitoes Stay Low, West Nile Positives Increase
August 8, 2022
Weekly Update – August 22nd – Very Slight Uptick in Mosquitoes
August 30, 2022
Nuisance mosquitoes remained low last week before the rain came.
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.
On Monday, August 8th there were very few mosquitoes collected in traps and sweep net collections during the MMCD Monday night surveillance. However, this was before any impact would be seen from the rain that fell the weekend of August 6-7 and the end of the week on August 11-12. Several areas of the District received over an inch of rain during one or both of those events which may have been enough to hatch some of the floodwater mosquito eggs that have been lying in wait all summer.
According to MMCD assistant entomologist, Dr. Scott Larson, "we had ZERO traps that captured more than 130 human-biting mosquitoes this week. Depending on how much rain we received [at the end of last week], we are still somewhere between 5 and 6 inches of rain below normal for the summer."
Here are the mosquito trap counts from last Monday, August 8th:
More mosquitoes test positive for West Nile virus in Anoka and Ramsey Counties.
Several of the same areas in the Twin Cities collected more mosquitoes that tested positive for West Nile virus last week showing that the disease is active among mosquitoes and birds in the area. New positive samples came in from Anoka and Ramsey County last week, adding to the samples that have already tested positive in Dakota and Hennepin County, according to MMCD Vector Ecologist Kirk Johnson.
As evident in the maps above, MMCD gravid traps, which are designed to collect container breeding mosquitoes like the Culex species that vectors West Nile virus, have been collecting more than our CO2 traps lately. August is a month that usually has declining numbers of nuisance mosquitoes at the same time as increasing risk for West Nile virus.
If you need tips to reduce your risk of mosquito-borne disease (and mosquito annoyance in general) check out our Resident's Guide!
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