This story could make you feel itchy all over.

Researchers who are trying to make them go away, but nothing seems to be working.

Bed bugs are just flat out ugly and gross. Like cockroaches, they won't go away.

"We've got bed bug problems all over the United States," said Dini Miller, of Virginia Tech urban pest management.

Inside the Dodson Urban Pest Management Lab at Virginia Tech, Miller teaches students how easily bed bugs can spread.

"There's lots of places for the bed bugs to hide,” Miller said. “They can move through the walls from one unit to another."

Across the hall, graduate student and lab tech Mark Petersen is breathing hard on a cup full of nasty bed bugs.

"I'm trying to get them excited so they can let go of the mesh screen. They react to CO2,” Petersen said.

Using tweezers, Petersen is separating the male bed bugs from the females. Yes, he can tell the difference.

"I have felt that they're crawling around me sometimes even if I know they're not,” Petersen said. “You spend all day looking at them. It gets in your head."

Experts say DNA shows a strong theory about how bed bugs may have swarmed back into America. So far, no chemical is killing them.

"A lot of those bed bugs are genetically connected to Eastern Europe and if you think about when the Berlin Wall came down and the fact that we started seeing bed bugs in this country in the 90's, really the late 90's, there's directly a tie," Miller said.

Students at the Dodson Lab are taught various treatment options, but so far nothing is working.

"But here's the thing, DDT and those products that we relied on, there is a lot of data that suggests that bed bugs became resistant to that stuff within eight years of its use," Miller said.