The stink bugs are back, and that means Bill Gallegor is busy.
"You almost went to voice mail," said Mr. Gallegor, vice president of Allegheny Pest Control in Jefferson Hills, when reached by phone this week.
He had just finished spraying the outside of one house with pesticide and was on his way to treat another. A flurry of calls for help stomping out stink bugs started coming into his office two weeks ago.
"They don't pose any threat, but still people don't want them," he said. "They are ugly."
By now, the stink bug needs no introduction.
The brown marmorated stink bug, a foul-smelling, shield-shaped insect native to Asia, was first observed in 1998 in Allentown, Pa., according to a fact sheet created by Penn State's College of Agricultural Sciences.
They appeared in smaller numbers throughout the Mid-Atlantic for years, then attracted a large amount of attention in 2010, when a major stink bug population caused widespread crop damage, said Tracy Leskey, a research entomologist at the U.S. Department of Agriculture's Agricultural Research Service. She is also co-leader of a stink bug working group based in West Virginia that is collecting data on the bug.
According to information posted on the group's website, www.stopbmsb.org, the stink bug has now been detected in 38 states. It has caused severe agricultural and nuisance problems in six, including Pennsylvania, West Virginia and Maryland.
The fall of 2010 was also the first season that the stink bugs "really infested the area," said Mr. Gallegor, who had only received occasional calls in earlier years.
"It was just nonstop, daily," he said. "That's all we did."
The next year, he had far fewer calls, and Ms. Leskey said the population of stink bug did seem smaller in the fall of 2011 and spring of 2012, perhaps due in part to late season weather patterns such as tropical storms. Because the insect is relatively new to the region, researchers are still trying to understand what factors drive the bug's population growth, she said.
Right now, she said, entomologists are seeing an increase in stink bug activity, a trend that she expects will continue for several more weeks.
"We've seen across many locations this year that the populations are up significantly over where they were in the fall of 2011," said Ms. Leskey, who said she is seeing "plenty" of stink bugs at her own home in Kearneysville, W.Va.
Fall is when stink bugs in Pennsylvania and many other states flee from crop fields and wood lots and look for a place to spend the winter, said John Tooker, an assistant professor of entomology and an extension specialist at Penn State.
"They are trying to find a happy little spot," he said.
Happiness for a stink bug often means a headache for humans like John Steele, 49, a technician at Evey True Value Hardware in Bethel Park.
Mr. Steele returned to his home in South Park on Tuesday night and said it looked like "someone took a shotgun and pepper sprayed the back of the house." He estimated that about 200 stink bugs were clinging to the white aluminum siding of his home.
"[That] was the worst I've seen in about a year," he said.
Andrew Amrhein, owner of Evey Hardware, said Wednesday he had sold 200 units of stink bug traps or spray in just the previous 24 hours.
"It's been crazy the past couple of days," he said. One customer told Mr. Amrhein he had 4,000 to 5,000 stink bugs in his home already, and another customer had up to 500.
"They are just anxious to find ways to get rid of them, and or at least keep them out of the house," he said. His store offers a pesticide spray for stink bugs, an outdoor trap and a light to attract the bugs into the trap, all of which Mr. Amrhein said his customers report are effective.
One of the traps on display held a few of the dead insects, stink bugs that had been caught after they entered the store.
People bothered by stink bugs can hire a company, buy an outdoor spray labeled for crawling insects, seal openings in their homes and vacuum up stink bugs that have gotten inside their house, said Allegheny County Health Department entomologist Bill Todaro.
Still, the stink bug can be a hard one to squash. And one of the most challenging parts of his job, Mr. Gallegor said, is explaining to people that the stink bug cannot be eliminated the way that other pests, such as ants or mice, can.
"These, you just can't," he said. "They just keep coming in droves. The best you can do is control them."
Kaitlynn Riely: firstname.lastname@example.org or 412-263-1707. First Published October 5, 2012 4:00 AM