After receiving a tip about the ad, which included photos of both the iPod touch and marijuana (see below), police officers sent an e-mail purporting to be interested in the exchange. When the police met up under the pretense of completing the trade, 20-year-olds Jacob Walker and Jacob Veldare were instead arrested when Walker offered up the marijuana. Both now face charges for possession and the attempted sale of an illegal substance.

Not only were the two unwise enough to post pictures of marijuana on Craiglist, but they were also gullible enough to believe that anyone would trade a 32G iPad, which costs $599 for the Wi-Fi version and $729.00 for the 3G version, for a $299 32G iPod touch and a quarter ounce of marijuana of dubious quality.

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Sniffing Out Bedbugs

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“Except that there’s nothing typical about this business,” said his handler, Jeremy Ecker, 35, whose six-month-old company, the Bed Bug Inspectors, has vetted hotels, college dorms and Midtown office buildings, suburban homes, bare-bones Brooklyn rentals and tony Manhattan co-ops. (Mr. Ecker, who charges $350 for a residential inspection, is an independent inspector, meaning he has no affiliation with an exterminator, though many hire him to check a property they have treated.)

Increasingly, real estate lawyers are urging buyers in contract to inspect apartments before they close, and in their advertising, many pest control companies exhort would-be tenants to “inspect before you rent.” And dogs like Cruiser can inspect a room in minutes, whereas lesser mammals like human beings need hours to conduct a visual inspection.

Bedbug-sniffing dogs, adorable yet stunningly accurate — entomology researchers at the University of Florida report that well-trained dogs can detect a single live bug or egg with 96 percent accuracy — are the new and furry front line in an escalating and confounding domestic war.

While experts cite a host of reasons for the upsurge, they agree on one thing: the bugs, which were mostly eradicated in this country at midcentury by now-banned pesticides like DDT but remained a constant scourge overseas, are finding their way back to the United States through an increase in global travel.

And in cities like New York, where neighbors are often separated only by bricks and mortar, one person’s infestation is everybody’s problem, since bedbugs can crawl through walls and along wiring and pipes, and hitchhike on clothing, furniture, luggage and more. In this city of 8.3 million, it seems as if everyone has a bedbug story.

Just ask Gale A. Brewer, a self-appointed bedbug evangelist and a City Council member from the Upper West Side. She prodded the Mayor’s office to convene a bedbug advisory committee last fall, after years of what she and others felt were woeful public policy inadequacies in the face of the relentless advances of what some have called “the pest of the century.” (The committee — entomologists, civic policy experts and advocates for children, the elderly and others — will issue its recommendations next month.)

The breadth and scope of the problem has been captured anecdotally in anguished tales — the family living in a tent outside their lovely-but-infested Long Island home, the woman in the Upper West Side one-bedroom who spent $9,500 on extermination and lived out of plastic bags, at friends’ apartments, for three months — posted on blogs like bedbugger and newyorkvsbedbugs, the likes of which have been spreading like, well, bedbugs, over the last few years. They are told over and over at community board hearings presided over by Ms. Brewer and others, and recorded in mainstream media. Another picture, though still incomplete, comes from the city’s Department of Housing Preservation and Development, which has been tracking bedbug complaints and violations through calls to the 311 help line. Consider that six years ago, there were 537 bedbug complaints and 82 violations (in other words, verified infestations); last year, complaints topped out at nearly 11,000, with 4,084 violations cited (nearly double that of the previous year).

But the complaints registered with the department and 311 relate only to rental properties; reports of bedbugs scampering through the private sanctums of hotels, co-ops and condos, colleges and office buildings remain largely uncounted, though real estate lawyers and brokers report that co-op minutes reveal a world that’s just as infested as the rest of the city.

In the last three months, and for the first time in her 21-year career, for example, Lori Braverman, a Manhattan real estate lawyer, advised buyers she was representing in three deals to inspect apartments they were in contract for, having noted in the co-op boards’ minutes instances of bedbugs in their buildings. “One was described as a ‘significant infestation,’” she said. “It’s the deep, dark secret of co-ops and condos.” (All three checked out clean, including a classic five on the Upper West Side inspected by Cruiser.) Still, as Ms. Brewer said darkly, “Those bugs are everywhere.”

After a day or two with Cruiser, one would have to agree.

NINE-THIRTY in the morning in Borough Park, Brooklyn, at the home of a family of seven, two of them still in diapers: the family was poised to move to a new house, their things in boxes, the rooms askew, to the horror of the mother, who had to welcome a reporter and a photographer into the pre-move disarray. (Like all the bedbug sufferers in this story, she asked not to be identified because of the stigma surrounding the pests.)

Cruiser had been invited because the mother had found a dead bedbug floating in the bath of one child the night before, and she wanted to make sure, if there was an infestation, that it didn’t travel to their new home. The house next door had had a problem, she said, and she knew bedbugs travel easily through walls. All this was related to Mr. Ecker, while Oscar Rincon, his colleague, waited outside with Cruiser.

“I don’t want to know the details,” Mr. Rincon said later, lest the knowledge affect his body language and interfere with the dog’s inspection.

Mr. Rincon, 42, is an old friend of Mr. Ecker’s who worked for years at the North Shore Animal League. He and Mr. Ecker, Cruiser and his partner, a beagle called Freedom, were all trained for their work at J&K Canine Academy in High Springs, Fla., where rescue dogs are schooled in the scent detection of termites, bedbugs, bombs, some cancers and canker, a scourge on citrus crops. The school has an ongoing relationship with the University of Florida, which has been testing its results.

In two weeks training with Cruiser and Freedom, Mr. Ecker and Mr. Rincon learned how to hide live hives of bedbugs — little gangs of bugs tucked into vials fitted with mesh covers, so the scent can travel, but the bugs stay put — and work with the dogs in constantly changing scenarios (hiding bugs in high cupboards, in drawers, under rugs and so forth). Like all scent-detecting dogs, Cruiser and Freedom work for food; put another way, they are fed only when they find their target, which keeps them accurate and keen on their jobs.

This poses challenges, however, for a dog handler. Back home in Fresh Meadows, Queens, Mr. Ecker discovered pretty quickly that his new career required an extreme lifestyle commitment. Not only would he have to live with bedbugs to train and feed his new roommates, Cruiser and Freedom, he would have to feed the bugs, too. Remember that dinner for a bedbug is a nice long quaff of human blood; Mr. Ecker rolled up a sleeve to reveal a horrifying tattoo of old bites. (Bedbugs don’t carry disease, but their bites can itch like crazy.)

Happily, the bugs need to eat only once a month or less, he said. “It’s not so bad. You can hardly feel it.”

A few days later at his home, Mr. Ecker demonstrated, tipping a vial of bugs onto his forearm, which the critters latched on to like hungry newborns, their bodies quickly swelling with blood. Meanwhile, Mr. Rincon was cleaning vials, ensuring that the dogs learn to detect only live bugs and eggs. He swept the debris — bedbug feces, maybe some eggs — into plastic cups, which he filled with water and stuck in the freezer, since extreme temperatures are proven bug snuffers.

“You have to be very focused,” Mr. Ecker said. “You can’t sneeze, or answer the phone. The cat has to be out of the room. Want to try?”

BACK in Borough Park, Cruiser had started to work. Mr. Rincon wiped his paws with a towel and began leading him around the house. The family’s boxed possessions, stacked in the basement, were quickly vetted. But a wooden crib in a child’s room gave Cruiser pause. The father turned it back to front and the dog began pawing the mattress, signaling an alert. (What Cruiser does is detect the scent of a bug or an egg; it’s up to an exterminator, said Mr. Ecker, to visually confirm the presence of bedbugs in the spots a dog has noted.)

The mother exhaled slowly. “That’s where my 2 ½-year-old sleeps,” she said. She had the expression, a sort of satisfied wince, familiar to parents everywhere, when a nagging suspicion — the toe is broken, the teeth need braces, the itchy scalp is really lice — has been confirmed.

Returning Cruiser to a crate in the back of his white Subaru Outback, Mr. Ecker, who had been in the extermination business for six years, reflected on his new career. Since he and Mr. Rincon returned from Florida in September, they’ve done hundreds of inspections. Despite the ick factor, “it’s very rewarding work,” he said. “We get to walk dogs for a living and we help people get peace of mind.”

Mr. Rincon added: “We see people who literally haven’t slept for weeks. They think everything is a bedbug. At a place in Jersey, the wife was a total wreck. She’d saved 15 samples of stuff, thinking it was bedbugs.”

It was mostly lint, as it turned out.

A mother of 7-month-old twins in a bedroom community outside of New York was not so lucky. It was Cruiser’s last stop of the day; after Borough Park, he’d inspected a Midtown office and an apartment in Riverdale. Both were bedbug-free, the day’s happy endings. Outside the city, the rain was still coming down in sheets. A Manhattan-dwelling relative of the mother had had bedbugs, perhaps the source, she said, of her house’s infestation, which she had had heat-treated, at a cost of $5,000. (Many sufferers with animals or young children choose this nontoxic method, in which very hot air is channeled into a space.)

She and her husband and their young family had decamped to a hotel. Back in her pristinely renovated 19th-century brick row house a week later, however, she was convinced she was being bitten again. The woman extended a graceful bare foot with a large, angry welt on the arch. She had called the pest control company she had used, but they were backed up on inspections and couldn’t promise a dog for another week. “I can’t wait that long,” she said.

When Cruiser arrived, he greeted the woman by placing his paws on her knees.

“Does that mean I’ve got them?” she wondered. “I feel like one big bug. If I can get through this, having twins isn’t going to be an issue.”

Cruiser spent 15 minutes at the house and alerted four times, scratching a parlor-floor loveseat, an upholstered side chair nearby, the mother’s side of the bed and a small black suitcase in a closet.

The mother’s eyes welled. “I have to remember no one is sick, no one has cancer,” she said. “Is it possible, when we went to the hotel, I brought them with me and then brought them back?”

“It’s possible,” Mr. Ecker said. “I’m sorry.”

Cruiser insinuated his wet nose into the reporter’s hand, and she scratched his silky ears.

Back in the car, she wondered: Shouldn’t the mother wrap the couch, the chair and the suitcase in plastic? What about her mattress? Does the inspection mean that heat treatment doesn’t work? Should the reporter, who had taken off her muddy boots in the house, throw away her socks?

Mr. Ecker shook his head. “What if I tell her to do one thing and it contradicts the pest-control company’s plans?” he said, referring to the client. “There’s nothing wrong with heat. There’s more than one way to cut apples.”

He added: “We’ve never taken a bug home with us. They’re not like fleas. They don’t jump on you.”

Bedbugs need time to get to know you, he explained. A short visit to a bedbug lair poses no risks. Still, as Mr. Rincon pointed out, “I never sit down.”

Moving Them Out

In the last several years, bedbug infestations have increased exponentially in New York City, but so have the resources to deal with them. The city offers a guide at nyc.gov. Bedbugger.com, a blog, is a Baedeker for treatment and a group memoir; newyorkvsbedbugs.org focuses more on city policies than remediation.

Think you have bedbugs? Bites might be the first sign, but not everyone reacts the same way: on some they look like welts or hives, on others mosquito bites and some people don’t react at all. Once you’ve met a bedbug, though, you won’t mistake it for anything else. The bugs look different at each life stage: the eggs are clear and the size of a pencil point, the babies are semi-transparent and poppy seed-size and adults are rust-colored and as big as an apple seed. The city’s Web site advises using an exterminator that describes itself as an “integrated pest management” service; make sure it is registered with the New York State Department of Environmental Conservation; ( 718) 482-4994 or go to www.dec.ny.gov.

To reach the Bed Bug Inspectors: (917) 455-6865.