Weekly Update – June 11th – Frequent Rains Bring Us Back to Average for Mosquitoes

Mosquito numbers are back on "normal" pace bringing the highest per trap average of 2024 so far.

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.

After a surge above the 10-year average and one week where things dipped below, we are back to "normal" in terms of the average number of mosquitoes collected in CO2 traps. Frequent rains for the past several weeks have created high water levels which often means more mosquito eggs hatch and become abundant in the weeks that follow. With several inches of rain in the forecast between now and the weekend, it's likely these numbers will continue to rise.

According to MMCD assistant entomologist Dr. Scott Larson, "like last year, the spring Aedes are wildly abundant compared to the long-term average.  Also, they peaked last week (which is 2 weeks later than usual) and/ or there were 2 peaks." The entomology lab is still determining if spring mosquito species are going to begin to subside, but this is definitely an unusual year. The graph below demonstrates what Larson was referencing in regards to spring species:

Hot spots remain this week in northern Anoka and Washington Counties along with spots in Carver and Hennepin Counties. Black fly numbers declined this week, though they are still high in southeast Dakota County along the river.

Here are the mosquito trap counts from last Monday-Tuesday, June 10th-11th: