The old admonition to "sleep tight and don't let the bedbugs bite" turns out to be harder than we thought it was, especially if you're a frequent traveler who spends time in hotels.

My Oct. 19 column about what I need in a good hotel room, concluding with an invitation for readers to say what their requirements are, generated a great response, with almost 80 people sending suggestions. I summarized your responses in the Nov. 2 column.

Out of all the messages, one intrigued me the most. Clay Scherer, an entomologist who works for DuPont Co., researching ways to control bedbugs, described what he does when traveling to avoid encountering the little bloodsucking critters.

Having never been attacked myself, as far as I know, I had not taken bedbugs very seriously, and written nothing about them. But after some online research and interviews with Scherer and another insect scientist, I've learned why they've become a greater problem in recent years, how tough they are to kill, and some tips for avoiding them.

Lots of information about the bugs and how travelers can deal with them, on the road or at home, can be found at www.bedbugcentral.com. The Web site is a division of Cooper Pest Solutions Inc., of Lawrenceville, N.J., and is run by the firm's technical director, entomologist Richard Cooper. He's the other expert I interviewed.

Bedbugs, once thought of as a problem just in cheap hotels with poor sanitation, actually can infest any place where people move in and out frequently: hotels, college dorms, apartment buildings. From there, they easily hitchhike on clothing or in luggage to a home or office.

"It doesn't matter whether it's a high-end or low-end hotel; all are at risk, and all types have been known to be infested," Scherer said.

Members of the Greater Philadelphia Hotel Association assert that they don't have a bedbug problem. "They're very guarded about it," association executive director Ed Grose told me last week. "But if I put on a seminar about bedbugs, they're very interested."

Bedbugs were largely controlled with powerful insecticides just after World War II, but they have reemerged since DDT and other such weapons were banned as harmful to humans. They're tough creatures, and because no substitutes for the older insecticides have been developed, "there is no surefire way to control bedbugs yet," Scherer said.

Bedbugs attack at night, sucking blood from their victims. Most people don't feel them at work and won't know they've been bitten until small red welts, similar to a mosquito bite, appear on the skin several days to a week later. Otherwise, bedbugs aren't harmful to humans.

Scientists theorize that bedbugs have become more prevalent in recent years and can be found in many hotels because of the growth of international travel. Without knowing it, travelers transport them from one hotel to the next.

Scherer says he has a routine as soon as he checks into a hotel room. He looks behind the headboard of the bed for telltale signs, including the bugs themselves or their droppings. He puts his suitcase on a hard surface, such as a desk or tabletop, rather than on a folding luggage stand where bedbugs could be hiding in cracks and crevices.

(Another interesting e-mail: Jim McAuliff, of Hatfield, who describes himself as a "garage inventor," has a patent pending on a folding luggage shelf that attaches to a hotel room wall. He hasn't sold any of the devices yet, but I will report on it if hotels start using them.)

Richard Cooper, who in addition to contributing to the bedbugcentral Web site has written manuals on dealing with them, says it's unlikely you will be able to detect the pests with just a cursory inspection of a hotel room. It may require dismantling the bed and looking inside the mattress, steps that are impractical and maybe impossible.

Instead, Cooper travels only with clothes that can be washed in hot water once he gets home, which will kill the pests if they're on the clothing.

Equally important, while he is occupying a room, Cooper encases his toiletries, laptop, and carrying case, and his suitcase in large plastic bags so that no bugs can get in and be carried home.

Once he gets home, he inspects everything for signs of bugs before taking it into the house, and he uses a large collapsible bag with a heater and fan attachment to "debug" anything that cannot be washed in hot water.

"Once your home is infested, it's life-altering," Cooper said, because ridding a house or apartment of bedbugs can be far more troublesome and expensive than keeping them out in the first place. Putting mattresses in zippered plastic cases is one of the most effective ways of depriving bedbugs of a place to live and breed, he said.

"Simple measures can be taken," he said. "Don't get hysterical, and don't stop traveling. But when you travel, be smart about it."

Contact Tom Belden at 215-854-2454 or tbelden@phillynews.com.