Bed bugs make entomologists itch, too

Bed bug

Anything that sucks our blood while we lie in bed sleeping is bound to stir strong feelings. Think vampires and the many movies they have inspired even though vampires are at best folklore.

Bed bugs are real. They’re nocturnal but will come out during the day if they’re really hungry. They cannot live without human blood. They’re small but still visible. And as six-legged creepy crawlies their ick factor outranks any of the 170 movie versions of Count Dracula.

They’re also on the rebound.

A century ago, “Sleep tight, don’t let the bed bugs bite,” was not a children’s book. It was something parents said when they tucked in their children at night, and they meant it. Then the insects stopped being a pest in the U.S.

In the early 1990s, they were back in hotels, motels and private homes. Two decades later, the insects are becoming a nightmare in low-income housing, nursing homes and apartment buildings, said Coby Schal, an entomologist at N.C. State University who is a bed bug and cockroach expert.

“But it’s just the beginning of the problem,” Schal said Tuesday during a pizza lunch talk he gave at Sigma Xi in Research Triangle Park.

Coby Schal

Schal suggested the spreading U.S. bed bug infestation is a result of globalization. Based on genetic tests, he said, it looks like people and goods traveling around the world have brought along bed bugs from Latin America, Africa, Southeast Asia and Australia.

Most of the bed bugs now found in the U.S. are resistant to pyrethroids, a popular insecticide used in sprays and bed nets to kill mosquitoes that might carry malaria or dengue fever in the tropics. DDT, an insecticide banned in 1972 in the U.S., uses the same mechanism to kill insects as pyrethroids.

Once the bed bugs arrived on shore, just one female hitching a domestic ride could trigger an infestation.

On U.S. maps that track infestation reports, New York City and areas along the East Coast are red splotches. Single red dots are sprinkled all across the country.

One of those maps was part of Schal’s presentation. “Very soon that map is going to be all red,” he said.

No wonder bed bugs have been the topic of newspapers stories (here is one from the New York Times), blogs (like this one) and an NPR Talk of the Nation segment with Science Friday host Ira Flatow. There’s even an educational Youtube video with Isabella Rossellini about bed bugs’ unusual way to mate.

“Bed bugs have a very cool sex life,” Schal said.

A male bug injects his sperm into a female’s blood with the help of a penis that looks like a hypodermic needle. After the first time, female bed bugs tend to leave to avoid mating again, Schal said. But a mated female can store sperm for her entire life and start an infestation of a multi-story apartment building that can cost more than $50,000 to exterminate. (Read about the bed bug infestation in the Sir Walter Apartments in Raleigh here.)

Bed bugs don’t carry diseases like a relative, the kissing bug, or mosquitoes. An anesthetic they use takes the sting out of their bite. In about half of all cases, however, the anticoagulant bed bugs use to keep the blood from clotting causes an immune response and red, itchy marks on the skin. Those marks can turn into pustules as Schal experienced himself after letting bed bugs feed on his arm for about two weeks in his NCSU lab.

As an entomologist, Schal goes pretty far to study insects others would rather avoid. He’s even toying with an extermination idea that involves delivering a deadly insecticide during a bed bug’s blood meal. The idea draws on topical flea killers used on cats and dogs, but in the case of bed bugs we would be the bait.

Outside his lab he also prefers to avoid bed bug bites.

In hotel rooms, he said, he never puts his suitcase on a bed or against a wall and he always carries a flash light and dental mirror to check the seams of mattresses and the bed frame and headboard. He said he looks for the telltale black dots of bed bug poop.

For more interesting articles about laboratory equipment such as a thorough review of autoclaves, spectrophotometers, incubators, and digital scales, go to scienceinthetriangle.