How MMCD Uses Drones for Mosquito Control to Save Time and Improve Safety
July 25, 2023
Weekly Update – August 7th – West Nile Risk Increases, Floodwater Mosquitoes Drop
August 15, 2023
Another dry year means mosquitoes are staying below the 10-year average by a significant amount.
Drought conditions keep most mosquito numbers low, but more samples are testing positive for West Nile virus.
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 entirety of the Twin Cities now finds itself under severe drought conditions with a couple of pockets even reaching extreme drought according to the U.S. Drought Monitor. This lack of precipitation has been the cause of overall mosquito numbers that are well below the 10-year average. This past week saw pockets of rain of over an inch fall in the southern half of the Twin Cities on Wednesday and in norther Anoka County on Thursday. There was enough rain in some spots to hatch a significant amount of mosquitoes and MMCD staff and helicopters are out treating the most highly productive areas. We will find out in the coming weeks if that rain was enough to make an impact on the mosquito total.
According to MMCD assistant entomologist Dr. Scott Larson, "We saw a very small increase in the number of adult mosquitoes this week compared to last week. We are still seeing [around] 200 less human-biting mosquitoes per trap compared to the 10-year average." Larson notes than in the initial samples, it does not appear that this week's rain made much of an impact. We are also seeing higher than average Culex mosquito numbers, which is common for hot, dry conditions.
Here are the mosquito trap counts from last Monday, July 24th:
A surge of new mosquito samples test positive for West Nile virus and now 5 District counties have reported multiple positives.
Since our last weekly update an additional 23 samples of mosquitoes have tested positive for West Nile virus and now 5 Twin Cities counties have had multiple positive samples.
MMCD Vector Ecologist Kirk Johnson reports that in the past week samples collected in Anoka, Dakota, Hennepin, and Ramsey County have all tested positive for West Nile virus. This increase fits with the behavior of Culex mosquitoes (Minnesota's West Nile vector) which tend to increase as towards the end of the summer and thrive in hot conditions.
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.
MPR Reports on climate change impact of vector-borne disease
West Nile virus isn't the only concerning disease that we have in Minnesota. Mosquitoes and ticks are capable of spreading multiple diseases and climate change is making summer hotter and longer which gives more opportunities for the diseases to thrive.
This week MMCD's Kirk Johnson was on MPR News with Angela Davis as a guest along with other scientists to talk about the impact of a warming climate on vector-borne disease.
