Is It Cold Enough Yet? What Winter Can Tell Us About Insects in 2021
Anthony Hanson, IPM Extension Educator & Robert Koch, Extension entomologist
On February 15, 2021, much of southern Minnesota saw morning low temperatures below -20°F, and much of the northern part of the state saw lows near or under -30°F preceded by similar subzero temperatures earlier in the month (Figure 1). Generally, this degree of a cold is troublesome for farmers ranging from issues with alfalfa winter kill to waterers freezing up for livestock producers. However, the cold can be a welcome event for pest management, especially with fewer winters in recent years reaching these annual lows.
Cold winters help prevent many potential pest insects from establishing here or requires species that cannot survive our winters, like potato leaf hopper or black cutworm, to migrate up from southern states. Extreme cold can also knock back species that are established here.
Insect cold tolerance
Outlook for 2021
In 2021, this cold snap may help reduce aphid populations to a degree, but do not expect a similar amount of winter control of soybean aphid as we likely had in 2019. Many insect populations can grow quickly, so even a small percent of the surviving population can still cause problems for soybean growers under the right conditions. In short, there may be a somewhat reduced risk of soybean aphid issues this year due to the cold, but problem fields could still easily occur across the state.
Start scouting early in the year so you can stay on top of soybean aphid populations that may develop in your area. For more information, visit Extension’s soybean aphid webpage.
If you have questions about these maps or pest forecasting, contact Dr. Anthony Hanson (email@example.com).