Prompts winter weather advisories as cold air moves in Friday night

MPR News helps you turn down the noise and build shared understanding. Turn up your support for this public resource and keep trusted journalism accessible to all. 

Turn Up Your Support

 is likely to have consequences for the summer of 2024. 

Our lack of extreme cold last winter means that many insects that are considered pests survived the winter in greater than usual numbers. That may have big implications for ash trees and Minnesota crops this summer. 

Anthony Hanson is the regional extension educator for field crops integrated pest management at the University of Minnesota. He keeps track of winter temperatures and insect mortality in Minnesota’s typically frigid winters. 

 that suggests a very low insect mortality occurred this winter. He opens with comments on the nature of extreme cold in Minnesota and the likely impact of the lack of extreme cold last winter. 

The lack of extreme cold last winter means insect survival rates are high.

The coldest temperature at Minneapolis-St. Paul International Airport last winter was minus 8 degrees on Jan. 14-15. International Falls bottomed out at minus 23 degrees on Jan. 20. 

Anthony notes that the lack of extreme cold last winter means insect survival rates are likely much higher than in several winters. And it’s even warmer where those little critters can burrow a few inches into soils or tree bark. 

Anthony notes that insects like the soybean aphid escaped this winter with very little mortality in Minnesota.

Compare that map to Jan. 31, 2019, when the bitter polar vortex dropped temperatures to minus 30 or colder across much of Minnesota. Soybean aphid mortality was more than 90 to 95 percent across more than half of Minnesota. 

Our record-warm winter is not good news for stopping the recent attack of the emerald ash borer in Minnesota. The lack of extremely cold temperatures this winter suggests that most of will Minnesota see less than 5 to 10 percent ash borer mortality. 

Data from the National Oceanic and Atmospheric Administration and the nonprofit climate news and science group Climate Central show winters have warmed between 5 and 6 degrees on average in Minnesota since 1970. 

Anthony notes that many insects need only a few degrees warmer temperatures in winter to survive in greater numbers. That’s why these pests are sensitive to even relatively small changes in climate.

Our record-warm winter means it’s likely that farmers and ash trees may have a harder than usual time dealing with the potential for increased insect numbers this year.

Weather and Climate News

Updraft® - Minnesota Weather News

Paul Huttner

Author

Minnesota’s mildest winter on record wasn’t cold enough to kill many insect pests in Minnesota.

Warmest winter likely means aggressive emerald ash borer and crop pests this summer

Derek Montgomery for MPR News

Corn in eastern Carver County in July 2022

Paul Huttner/MPR News

Figure 1. Morning lows on Jan. 20, 2024; temperature data produced by NOAA obtained from U.S. National Phenology Network.

Predicted soybean aphid cold-exposure mortality 

Jump in emerald ash borers, crop pests likely after record-warm winter

Go Deeper.

Like this?