Anthony Hanson, IPM Extension Educator & Robert Koch, Extension entomologist Figure 1. Morning lows on Feb. 15, 2021; U.S. National Phenology Network: www.usanpn.org. 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 to...
