Beagle-human team keeps bedbugs from biting in Phila.

Heidi was being put to the test, and she knew it.

She also knew that if she didn't pass, she wouldn't be fed.

That's the boss' training rule: No bedbugs, no dinner.

So, as Marty Overline, the boss' son, grasped her leash tightly, Heidi, the 18-month-old beagle-turned-pest-management expert, moved ever so slowly across the floor of the multipurpose room at Opportunities Tower III in West Philadelphia, sniffing all the while for that distinctive, sickeningly sweet smell that can permeate glass.

Four upholstered chairs and less than 30 seconds later, Heidi had what she came for: a vial containing a bedbug planted in that fourth chair by the boss, Martin Overline, owner of Aardvark Pest Management, of Frankford.

Overline held the vial up for inspection. Heidi said nothing, preoccupied with her meal.

"That is how she is trained, reinforced, and fed," Overline said. "She is fed at no other time."

Heidi has a degree from J&K Canine Academy in High Springs, Fla., and is one of just 50 bedbug-hunting dogs of all breeds nationwide.

Heidi signed on with the boss in April after four months at J&K. He paid $10,000 for her - a big expense for a small-business owner, "but I can only find bedbugs 30 percent of the time, and she can do it 90 percent," Overline said.

When you consider that bedbugs are the latest big thing in the pest-control business, that expense appears justified.

After almost a half-century of freedom from bedbugs, the beasts have reappeared in the United States with a vengeance, says the National Pest Management Association, in Fairfax, Va.

Chemicals - especially DDT - that eradicated bedbugs after World War II were deemed unsafe less than a decade ago, and nothing as successful has replaced them, Overline said.

Couple that with increased international travel and students from other countries' studying here, and here's the result:

Five or six years ago, pest-control companies reported one or two bedbug calls a year, the national association says. Now, they are reporting one or two a week - in fact, association members say calls are 50 times higher today than a few years ago.

You'll recall the saying, "Don't let the bedbugs bite!" Well, they do, and for blood. Their saliva may cause swelling in those bitten, but they do not typically leave a wound.

Overline, who began his pest-control business 15 years ago, received his bedbug education in the Air Force, when he was in charge of controlling infestations at a military hotel accommodating transients in Frankfurt, Germany.

"When I got home, the one thing I was glad to have left behind was bedbugs," Overline said.

The bugs are here now, though, and Overline started getting calls for help from colleges and universities, hotels, and the City of Philadelphia.

The biggest problem Overline faces in handling infestations is not six-legged, from mahogany to rust brown in color, with short golden body hair, and two antennae.

It is with the managers of hotels and university maintenance departments who believe that if the public found out that bedbugs were present, people would avoid their institutions like, well, the plague.

"They ask why I have to bring Heidi," Overline said. "I say, 'Because she's better at finding them than I am,' " especially because bedbugs are nocturnal.

Overline and the national association emphasize that bedbugs do not necessarily mean unsanitary conditions.

Cecilia Skipper and Steven Tilley second that emotion.

Skipper is site manager of Opportunities Tower III, which provides housing to low- and moderate-income senior citizens, while Tilley has been in charge of maintenance for 18 years.

"The problem is that people bring in a lot of used furniture to their apartments from friends or that they find because they often can't afford new things," Tilley said, adding that Overline, who routinely visits each month, "has taught me everything I know about bugs."

Except for the vial that Overline used for demonstration, there were no bedbugs present.

When Heidi does locate an infestation, Overline typically uses heat to eradicate the pests in a home-built contraption that uses materials from Home Depot and cost less than $500.

"I take everything the bedbugs may have been in contact with and put them in a box I make from 2-inch-thick hard-insulated foamboard," he said.

"Then I add space heaters and fans to boost the temperature," he said. "When the core temperature reaches 113 degrees or higher, the bedbugs die and their eggs burst."

Overline has done this 18 times in the last three months, with an unexpected victim besides the bugs in one instance.

"A copy of the Beatles' Abbey Road album," Overline said. "Warped it."