The Washington PostDemocracy Dies in Darkness

Polar vortex chill exterminated 95 percent of stink bugs in Va. Tech experiment

Virginia Tech entomology professor Thomas Kuhar found a 95% kill rate of overwintering stink bugs after the severe and prolonged cold weather associated with the <a href="">Arctic outbreaks in January</a> .  Kuhar concluded,  “There should be significant mortality of BMSB (brown marmorated stink bugs) and many other overwinter insects this year.” (Kevin Ambrose)

This spring, you may see and smell fewer of those foul stink bug pests, and you can thank the polar vortex.

The punishing, prolonged blasts of arctic air this January proved too much for most stinkbugs to overcome according to Virginia Tech field researchers.

Each fall, Virginia Tech entomology professor Thomas Kuhar and his team gather stink bugs that congregate on the outside of buildings.  The stink bugs are put into ventilated 5-gallon buckets filled with foam insulation tubes and then the buckets are stored outside for the winter, under a shelter.  Each bucket contains about 100 stink bugs.

The insulated buckets simulated the overwintering locations of stink bugs.  The bucket arrangements also help to keep the bugs in a dormant state of diapause while they await experiments in Kuhar’s Virginia Tech lab.

Stink bugs prefer to spend the winter under shingles, in attics, or in the walls of houses and office buildings.   As the temperature falls, the stink bugs change their physiology by increasing their cryoprotectants (antifreeze proteins) to prevent their body fluids from crystallizing.  This helps the bugs survive the winter’s sub-freezing temperatures.

The presence of stink bugs in the Washington, D.C. area was confirmed in 2007.  From 2007 to 2009, the bugs reproduced rapidly.  The stink bugs became a problem in this area in 2010.  The bug problem has continued to increase throughout the greater D.C. area in recent years.

Since the stink bug explosion, we’ve not had a severely cold winter to test their overwintering tenacity.  It was not even known if a Mid-Atlantic winter could be cold enough to freeze the bugs.  Stink bugs had survived lab tests where the temperature was reduced to near -20 C (-4 F).

Last month, Arctic air intrusions touted by the press as the “Polar Vortex” chilled much of the country.  In the Washington area, the temperature dropped to near the same level as the stink bug lab tests, to around zero, but the cold across the area persisted for many days.  Some of us stink bug haters wondered if the prolonged arctic freeze would impact the overwintering bugs?

Two weeks ago, Professor Kuhar pulled out his first set of insulated buckets for stink bug experiments.  Kuhar and his staff found that within the buckets of bugs there was a 95% kill rate from the sustained cold weather that occurred in January in Blacksburg (which is slightly colder than Washington).  The little stinkers had frozen to death!  So, it does appear that the stink bugs have a freezing point.

As a result of the high kill rate, Kuhar concluded, “There should be significant mortality of BMSB (brown marmorated stink bugs) and many other overwinter insects this year.”

Will there be a noticeable drop in the stink bug numbers this spring?  Will there be less crop-related problems from stink bugs during the 2014 growing season?  Will we see less stink bugs trying to hibernate in our homes next fall?  If we have another strong Polar Vortex chill, will it further reduce the stink bug numbers this year?  Only time will tell – but these initial test results are promising.

Have you noticed less stink bug activity in your home or office after the cold blasts that occurred in January?  Let us know your observations.


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