Chemical pesticides had all but wiped bed bugs out for decades, but many of those pesticides aren't used anymore and the bed bugs are back, and they're looking for a midnight snack.

They're called bed bugs because they live in the seams of mattresses and bite at night.

Nellie's landlord has tried for a year to rid her Milwaukee apartment of the pests.

"We was hoping it was getting better, we was hoping," Nellie's caregiver, Jan, said. "They (are) still in that bed, so they're still getting her at night."

When asked by WISN-TV in Milwaukee the rection when he tells people that bed bugs are biting them, Dave Kusnierek of Batzner Pest Control said, "Oh wow, well, they freak out."

Kusnierek said the cases of the creepy critters are multiplying.

"It's kind of a nasty pest that feeds on you. They're sucking your blood while you're sleeping," Kusnierek said.

"People just kinda get creeped out that there's things coming out at night feeding on them. The big ones are full-grown adults," University of Wisconsin entomologist Phil Pellitteri said.

Around UW-Madison, Pellitteri is known as the bug doctor. He's seeing more cases of bed bugs than ever and not just in homes.

"They're quite common in hotels, and the interesting thing is, they're nice hotels. It's not what people talk about 'flea bags,' that's not where I tend to see them," Pellitteri said.

Orkin Pest Control recently shot video in an out-of-state hotel. It shows an infestation of bed bugs, which experts say isn't surprising because one reason for the bugs' resurgence is an increase in international travel.

"Anybody can, unfortunately, run into bed bugs, and once you bring them in, they'll thrive in the kind of conditions we have in our homes," Pellitteri said.

And you can bring them in. In fact, for them to be there, someone has to bring them in. They don't fly or travel on their own. But you can carry them with you on pillows, or luggage, or maybe used furniture, and once they're in, they're tough to get out.

"They hide in the seams of beds in box springs, behind picture frames, dresser drawers, between electrical outlets," Kusnierek said.

But at night they come out and bite.

"Bed bugs are real sneaky in that they feed at the absolute quietest part of the night," Pellitteri said.

Most people don't feel the bites until later -- when they wake up with small welts and begin to itch. Although bed bugs stay hidden during the day, it's easy to see if they're there.

"Bed bugs are very messy feeders and so you tend to get a lot of blood spots on the sheets and elsewhere when the populations build so that's one of the giveaways," Pellitteri said.

You may also see dark spots and streaks on bedding. If you have bed bugs in your home, getting rid of them requires a professional exterminator.

It's a big job for some little bugs that many people didn't even know existed.

"It's really quite a shock that there are such things as bed bugs," Pellitteri said.

"Well, we know better. We know better," Jan said.

Bed bugs are survivors. They can multiply by the hundreds and can live up to a year without feeding.

The good news about them is that they are the only bloodfeeding insect that doesn't transmit any diseases.

Still, you want to keep them out of your home, and so the experts say to carefully inspect any used furniture, especially bedding before bringing it into your home.

When you travel, check the hotel bedding, and if you see signs of bed bugs, report it and ask for another room.

If you're worried you've come in contact with them while traveling, experts suggest vacuuming out the seams of your luggage before taking it into your home.

They can survive in any home environment. It has nothing to do with personal hygiene or the cleanliness of the home. If they're carried in, they'll live there.