MANKATO — Blood-sucking bed bugs have hitchhiked their way into Mankato bedrooms, and more are probably on the way.

“Bed bugs have a massively huge freak-out factor from everyone they touch,” said Stacy O’Reilly, president of Plunkett’s Pest Control Inc.

The paranoia is based more on the ick factor than an actual health threat: There are no documented cases of a disease being transmitted by a bed bug, she said.

A pair of pest control experts were in Mankato Wednesday to hold a class on bed bugs. It was organized by the Minnesota Multi-Housing Association, a trade group for managers of multi-unit housing.

They said bed bugs are making a comeback, and it’s only a matter of time before they become more common here.

“It is a train rolling down the track that nobody knows how to slow down at this time,” O’Reilly said.

She brought three dead bed bugs that had been plucked from a Mankato bedroom by a Plunkett employee en route to identification in the Twin Cities.

Of the two dozen or so attendees, about six raised their hands when asked if they’ve had bed bug problems. But at a similar class in Bloomington, O’Reilly said, 99 of 100 people raised their hands and the lucky one buried her face in her palms and groaned.

On the march

Todd Leyse, president of Adam’s Pest Control, said his company went decades without hearing about bed bugs. But in 1999 they got a few cases, then more the next year and so on.

Leyse and O’Reilly said no one knows for sure why bed bugs are becoming more prevalent. More travel could play a role, as could evolved pesticide resistance. The banning of the potent insecticide DDT also may have played a role.

New York City’s bed bug infestation also is worsening with more than 10,000 complaints to that city last year, one-third more than in 2007.

Whatever the reason, they’re here now and the pest control industry has spent the last decade catching up.

Bed bug biology

An adult bed bug is about one-fifth of an inch long — perhaps slightly larger than a wood tick — and very slim.

“If you can stick a credit card into a crack, a bed bug views that as the Taj Mahal, no problem,” O’Reilly said.

They emerge from their hiding spots at night, especially in the pre-dawn hours around 4 a.m., and crawl over their sleeping host.

Then “they wake up, stretch, get their morning cup of coffee, that’s you,” before retreating back to their hiding spot. They only suck blood for about five minutes.

About half of bite victims develop physical reactions, usually small red bumps that look like mosquito bites.

As pest control experts are learning, bed bugs are tough to kill and harder to eradicate.

Poisoned bait doesn’t work because bed bugs only eat mammalian blood. Pesticides are typically ineffective because the bugs “walk on their tippy-toes,” O’Reilly said, so they don’t absorb much of the poison. Starving them is difficult because they can go for more than a year without a blood meal.

Fumigation of living space is actually rare now, they said, because of the safety risks. Their companies don’t do it.

And throwing away infested furniture isn’t sufficient, either, as the bugs also hide elsewhere.

The closest thing to a “silver bullet” is heat, Leyse said. A few hours in 120-degree environment is too much for them.

But even after that, it’s just about impossible to prevent a re-infestation.

“Anyone who says, ‘I guarantee there are no bed bugs here,’ I look at them sideways,” Leyse said.

While it may sound self-serving, suggestions from O’Reilly and Leyse did not include reasonable do-it-yourself alternatives to exterminators.

Their case was backed up by Jennifer Hogan, a property manager from Dominium, a Plymouth-based company with Mankato clients.

“It’s not cheap to deal with,” she said of pest control.

That expense initially led her to use a cheaper remedy she found on the Internet. It didn’t work, and she eventually went to an exterminator, which did work.

Bed bugs infest rich and poor alike, and their presence is almost always no one’s fault, she said.

Still, the class’ attendees were not interested in talking on the record with a reporter about how they deal with bed bugs.

“You just can’t be embarrassed about it,” Hogan said.