First came the bedbugs. Then the bedbug-sniffing dogs. Now the pest industry is offering certification to companies that want to make sure their dogs and handlers really can sniff out the blood-sucking insects.

In most cases, bedbugs don’t emit an odor that the human nose can detect, according to David Latimer, whose family runs a canine scent detection business called Forensic and Scientific Investigations in Alabama. But the smell, described by some entomologists as sweet and sickly, is something dogs can be taught to sniff out, much the same way they can be trained to detect explosives and narcotics.

And because bedbugs are often difficult to find — they range from 1 to 7 millimeters in length — demand for bedbug-sniffing dogs is skyrocketing.

The increase “has been the most dramatic of any canine scent detection since bomb dogs after 9/11,” said Latimer, who is also the police chief and fire chief of Harpersville, Ala., population about 3,000.

In the past 12 months, his company has trained about 40 dogs, just for bedbugs. By comparison, about half a dozen dogs were trained to detect explosives, and an additional eight to 10 to look for narcotics.

It takes about three months, and with a good handler and under excellent clinical conditions the dogs can be “very, very proficient” in finding bedbugs, Latimer said.

His company relies on rescue dogs of mixed breeds, many of them beagles and terriers. Personality is more important than pedigree.

“Most of the dogs we adopt would not make very good pets,” Latimer said. “Periodically, someone calls us up and says their dog is nuts, that it can’t seem to contain itself. It’s like the dog needs a dose of ritalin when really all it needs is a job.”

At a three-day conference in Philadelphia starting June 1, the National Pest Management Association and several scent detection companies will be providing certification to teams of handlers and dogs, and training for handlers. To get certified, the dog and handler have to demonstrate they can find mesh-covered vials of five to 20 bedbugs hidden in hotel guest rooms.

“Some of the rooms will have them and the teams will have to find which ones have them” to pass certification, said Missy Henriksen, vice president of public affairs for the the pest management group.

About 250 people have signed up to attend the conference, she said, which will feature sessions on how best to work with scent detection dogs, including how to keep them from picking up bad habits such as alerting to odors other than the true target.

“You want to make sure they’re taught what to look for, and if they find a missing pb-and-j sandwich under a couch cushion that they’re not going to be rewarded,” Henriksen said.

The recent nationwide resurgence in bedbugs has led an increasing number of pest control companies to use specially trained dogs to help locate the bugs and their eggs, she said. Trained dogs cost between $10,000 and $12,000, she said, and some companies have used dogs that were not sufficiently trained.

In a study conducted by the pest association and the University of Kentucky last year, 95 percent of the 1,000 participating pest-management companies said that they had encountered an infestation in the past year, up from 25 percent a decade ago. The experts reported the highest incidences in private residences, followed by hotels and motels, college dorms, various modes of transportation, laundry facilities and movie theaters.

Experts suspect that the resurgence is related to resistance to available pesticides, greater mobility and travel, and lack of knowledge about pests that were virtually eradicated in the 1940s and 1950s.

They can live for months without a meal, hidden deep in mattress seams, baseboard cracks, and in clutter around beds. They travel easily, hitchhiking from person to person, city to city.

Experts recommend sealing mattresses and box springs in clear plastic coverings, and in hotel rooms carefully inspecting the wall behind the headboard for telltale signs of infestation: black specks (fecal matter), molten sheddings (like pencil shavings) or the bugs themselves (in their various stages of life).