This winter, especially January and February have been a bit cold, complete with ‘polar vortexes’ and lots of snow. There have been a couple of newspaper articles about how this will negatively impact insect pest populations, specifically brown marmorated stink bug. Is this true?
For BMSB, most likely NO. While insects do have something similar to antifreeze in their hemolymph (blood) there is a critical freezing temperature at which most species will die. Preliminary research by Dr. Tom Kuhar at Virginia Tech says the super cooling point – when the blood freezes – of BMSB is 5ºF. Populations in natural habitats may have suffered from the extreme cold weather. However, the majority of the BMSB population spends its winter with you, tucked inside the attic and under the eaves of houses, in boxes, under tarps etc. where it is warmer. They are in a reproductive diapause at this point, meaning that adult BMSB have physically prepared themselves to survive cold temperatures, and snow further acts to insulate the populations. There is a saying in Japan that lots of snow in the winter means lots of stink bugs (BMSB) in the summer! Research by Dr. K. Kiritani in Japan shows that BMSB is better adapted at surviving the winter than other stink bug species. There are many factors that contribute to winter mortality or survival and previous research suggests ~20% winter mortality for BMSB in any given year, regardless of weather.
So since the polar vortex may not keep the stink bugs at bay, keep monitoring your crops in the mid-late Spring for the initial dispersal.