Missy Henriksen – National Pest Management Association
Wednesday, January 8, 2014
Once my lips stopped shivering this morning, I sang the Baby it’s Cold Outside song all the way to work. As the car thermostat read a mere five degrees, it was only fitting. I suppose those who live in Chicago or the Dakotas may try and tell me I had it easy. I will gladly let them win the “we had it worse contest,” but regardless, cold is cold! Since everyone of late is writing about the freezing temperatures, I thought it would be appropriate to chime in with a perspective on what the unusually cold weather might mean in regard to bugs. In general, they don’t like this cold weather very much and a winter like this can only hurt insect populations. However, entomophobes – no rejoicing for you just yet.
Insects are equipped to avoid the bitter cold by migrating, entering houses and other structures, and burrowing below the freezing depth. Or, they can tolerate freezing temperatures by producing a substance similar to antifreeze, entering “diapause” (an overwintering like state) or by burrowing into leaf litter and soil. Their innate coping and adaptation skills are truly admirable and amazing. Believe it or not, many insects are able to withstand temperatures well below zero degrees. Invasive insects, however, may be more susceptible to death due to freezing depending on where they originated; emerald ash borer populations, for example, are believed to be greatly affected by Minnesota weather.
So the crystal ball question for those squeamish of spiders and insects has been “will this cold make bugs go away”? Answer: We aren’t sure. Generally, cold winters produce lower insect numbers than mild winters, but it is not 100% certain. It’s really the freeze-thaw cycles that are most determining for insect populations as the freezing causes ice crystals to form, which expands and ruptures cells. The more times this occurs, the greater the likelihood of severe damage or death. Gradually decreasing temperatures makes survival more likely. Hard freezes kill many insects, especially in southern states (perhaps due to rarity of this kind of weather and lack of snow cover). Extended freezes can potentially reach insects farther below ground and harm them. Snow cover insulates some overwintering insects and protects them from the extreme temperatures we have been experiencing across the country.
So, I guess we will just have to wait and see what Mother Nature has in store for us and the bugs throughout the rest of the winter season. Only time will tell.
*A special thank you to Dr. Bennett Jordan for his insight into this topic.