What impact do winter temperatures have on summer mosquitoes? (Fox 9 and WCCO)
February 24, 2021
KSTP: Minnesota could experience mild spring when it comes to mosquitoes, other insects
May 7, 2021
Field Operations Supervisor, Andrew M., from our East facility found the first larvae of 2021
Days with the temperature above 40 degrees in 2021 are tracking close to 2015-2017 when larval treatments began the first week of May.
There are a variety of factors that influence mosquito emergence in Minnesota during spring and one of the most important is the air and water temperature. At Metropolitan Mosquito Control District, we monitor air temperatures each year specifically looking at the number of days when the high is above 40 degrees. Our technical services team keeps track of this data and puts together a table comparing cumulative degree days over 40F to compare with previous years:
Based on the data we have through March 27th, 2021 is tracking ahead of the previous three years and more on pace with the temperatures in 2015, 2016, and 2017. During each of those years, the first week with cumulative temperatures above 40F totaling 200 came in mid-April and the first aerial larval treatments occurred during the first week in May.
With warmer temperatures expected at the end of this week as we head in to April, we may hit that 200 total as early as the middle of next week, but we still anticipate that our treatment schedule will follow 2015-2017 and begin in early May.
Mosquito larvae was found in March, but don't expect to see flying adult mosquitoes any time soon.
Our East facility gets the award for finding the first mosquito larvae of 2021 in a pond near their Oakdale office on March 18th. Many wetlands may have mosquito larvae right now, but that doesn't mean you should expect to see adult mosquitoes flying around any time soon. The cold water temperatures slow down the metamorphosis, meaning mosquitoes will remain as larvae for much longer before becoming pupae and finally emerging from the water as adult mosquitoes. Typically it won't be until summer - late May or early June - before water temperatures are warm enough that mosquitoes emerge from the water about one week after hatching.
Another important factor related to mosquito emergence is water level and as of now, water levels and annual precipitation for 2021 seem to be slightly lower than normal. In Minnesota, however, we can never count out an April blizzard or heavy rains to bring the water levels up!
If you have questions related to MMCD, mosquito biology, control methods, or anything else, reach out to us!
