Did Winter Kill All of the Stink Bugs?

What happens when stink bugs meet with the extreme cold temperatures of the Polar Vortex?

They die.

According to a recent experiment by a Virginia Tech entomology professor, this winter may prove too harsh for the invasive insects to survive, and that might affect how many of them resurface in the spring.

U.S. Department of Agriculture Research Entomologist Tracy Leskey said the insects, known as halyomorpha halys or brown marmorated stink bugs typically hibernate or 'overwinterize' in people's homes during winter months.

"When the bugs overwinterize, what they're doing is seeking sheltered locations where they can sit in a state of diapause until spring. They do seek specific places, under the siding of someone's house, or in an attic or shed," Leskey said.

The insects make their presence known through the sporadic release of a pungent odor.

According to the U.S. Department of Agriculture, in addition to being a household nuisance, stink bugs pose a major economic threat to producers of all kinds of crops, including grapes, apples, peaches, pears, citrus fruits, cherries, raspberries, green beans, soybeans, and cotton.

In January, when Virginia Tech entomology professor Thomas Kuhar placed hundreds of stink bugs in simulated winter weather conditions, he found that when the bugs were exposed to freezing and subfreezing temperatures for extended periods of time, 95-percent of them died.

The experiment results cause one to wonder if the Polar Vortex, which is scheduled to send another blast of subfreezing air to the east coast next week, will effect how many stink bugs  survive the winter, go on to breed and wreak havoc on Pa. farmers' crops later this year.

Assistant Professor of Entomology at Penn State University, John Tooker, said the results of Kuhar's research could predict a decreased presence of stink bugs.

"It provides some support for other research that says that at an average winter temperature of 39 degrees Fahrenheit, you should expect to see about a 31-percent mortality rate among overwintering adult stink bugs. If you drop that temperature from 39 degrees to say 20 degrees, you would expect to see that mortality rate increase," Tooker said.

"It is a reasonable hypothesis to make, that if there's a higher mortality in winter, then you would expect to see a smaller population out there in the spring and summer months."

According to Leskey, stink bugs are no strangers to cold weather. They originally hail from countries in Asia where temperatures typically hover around 20 degrees during winter months.

"These insects evolved in a location where they have cold temperatures and they have built-in mechanisms to deal with cold temperatures. So, they're pretty smart in the way that they evolve to survive the cold," Leskey said.

For Leskey, Kuhar's experiment indicates that there may be an exact temperature that proves to be deadly for stink bugs.

"Tom's data shows us that under certain conditions you could see the death of stink bugs. We have to research to find out what is that lethal temperature that causes them to die," she said.

According to Leskey, the Department of Agriculture has conducted similar research of stink bugs in winter weather conditions, and so far, they haven't seen drastic mortality rates like the ones seen in Kuhar's experiment.

Leskey said she's less confident that higher mortality rates during the winter will significantly change the number of stink bugs seen in warmer months.

"We've been going out and sampling locations that the bugs would have actually chosen and we haven’t seen a major impact so far. Were seeing what we would typically see. In the places where you typically find them, were seeing the normal mortality," she said. "Overall I don’t think people are going to see a big difference."

Tooker said he's holding out hope.

"There is a possibility that we could see less stink bugs," Tooker said. "I think it's okay to hope that that will be the case."

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