There may be a silver lining to this year's unseasonably cold weather: it could mean fewer pests this spring and summer.
Michael Raupp, an entomology professor at the University of Maryland, says many bugs that have plagued the D.C. region in the past won't be an issue thanks to this winter's polar vortex.
Raupp said some scientists at Virginia Tech, who saw temperatures on the Blacksburg, Va., campus drop to -5 degrees Fahrenheit this winter, have found a 95 percent mortality rate in stink bugs overwintering there.
Those findings may be too optimistic, though: other scientists have found a kill rate of just about 50 percent.
"What we're trying to do now is establish a baseline to see if [95 percent] is way out of the ballpark of ... the kind of kill rate when it comes to chilly temperatures," Raupp said during an interview Wednesday on The Kojo Nnamdi Show.
The survival of the brown marmorated stink bug, which invaded the D.C. region in 2010, depends mostly on how well they packed on weight last fall, Raupp said.
As temperatures get colder, the insects essentially create antifreeze in their bloodstream and reduce their metabolism in order to survive the winter. If bugs didn't eat well before the first freeze, their prospects of surviving are slim, Raupp said.
Aside from being welcome news to homeowners, fewer stink bugs could also be good for fruit growers. In the 2010 stink bug invasion, apple growers alone lost more than $37 million to the pests, Raupp said. Organic fruit and vegetables farmers, who have fewer tools to ward off the bugs, may also fare better this year if the stink bug population has declined.
"We're going to be cautiously optimistic that ... the polar vortex put the beat down on those guys" he said, but noted it would probably be two years before the cold's effects would truly be seen.
The cold won't so readily ward off some of the region's pests, though.
Mosquitoes in particular have a "very, very clever adaptation for withstanding cold," Raupp said. "They've seen this kind of cold in their history."
While we shouldn't necessarily expect a dent in mosquitoes, Raupp says, the cold could impact the insects' breeding pattern, which is based on the temperature.
"The longer we stay chilly, the further back in the season they [will start to lay eggs], which means less time to complete more generations" before it gets cold again, he said.
This year's cold weather also won't make much difference in the number of ticks in the area, but it could affect how many carry Lyme disease over the next several years. If the cold kills small mammals like mice, from whom ticks often pick up the disease's causal agent during their first meal, fewer ticks with the disease will survive.
Other insects for whom the cold will make it hard to survive: The harlequin beetle and the Emerald ash borer, which in recent years has killed tens of millions of ash trees nationwide.
"When temps drop to -20 to -25 degrees, that beetle is going to suffer very high levels of mortality and indeed they have," Raupp said.
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