The cold winter may not have killed as many stink bugs as it had originally been thought. Turns out, they have the good sense to come in from the cold.
“It would be nice to think that winter killed them,” said Stanton Gill of the University of Maryland Extension, where he specializes in integrated pest management. “But I doubt it. They are good at finding places to hunker down.”
While one researcher recently found that nearly 98% of stink bugs died in the cold, other experts expect to find no more than a 50% death rate over the winter. That is more than the normal 25% rate, but it won’t rid our homes of these annoying and destructive pests. They most likely snoozed through winter in warm spaces — like inside your house.
Other insects may not have been as fortunate. That includes bad guys like the insect that attacks Christmas trees and good guys like the Asian lady bug beetle, which eats aphids.
Gill began getting calls last month from people complaining that the brown stink bug, an invasive species that damages crops and drives homeowners crazy, was emerging from its hiding places.
“When it got really cold, people were turning up their heat and warming the inner core of their houses,” Gill said. The stink bugs were feeling the chill up there in the attic or in the rafters of the garage and migrated toward the heat, he said.
But when Virginia Tech entomologist noticed that his stink bug population had been devastated by the cold, the rumor started that stink bugs might have met their match in the polar vortex. Between 95 and 98 percent died when temperatures in Blacksburg dropped to 5 below. Their tissues had frozen.
But stink bugs don’t live in plastic buckets, exposed to the harshest temperatures. They hide under bark, in dead trees, in the gaps in siding. And in your attic.
We usually have (an over-winter death rate) of about 25%, but this year was much higher.
There is some thought that the kill rate might have reached 50 percent this winter, but scientists won’t know until the stink bug population emerges in the spring and becomes active. Even so, was it because of the cold? Or were other conditions responsible?
If you had to pick an insect that could survive a winter like this, it would be the stink bug. It has the behavior of seeking shelter.
The stink bug, which arrived from Asia and has no natural enemies in this country, was first noticed by homeowners near Allentown, Pa., in the mid-1990s. Since then, its numbers have exploded all over the Mid-Atlantic and it is found in 40 states, emerging now in the Pacific Northwest.
It is damaging fruit crops like apples and peaches and tomatoes, using its beak to pierce the soft skin and drink the juicy fluids inside. The holes that it leaves allow disease and other insects to destroy the fruit. But Raupp said scientists also have recorded damage on more than 150 varieties of trees and shrubs used in landscape plantings.
The nuisance potential of the stink bug is almost without equal. In the fall, after damaging crops, it sinks its beak into tree bark and damages trees. Then it moves into houses and barns for the winter.
Meanwhile, Tracy Leskey, an entomologist with the U.S. Department of Agriculture, who keeps track of stink bug damage said she is seeing about a 50% kill rate from winter cold.
For help exterminating stink bugs this Spring, contact EHS Pest.