For 60 years, Americans thought they'd vanquished bedbugs forever. They were wrong. Horribly, horribly wrong.

Bedbugs have been a staple of American life since the Mayflower. In 1926, infestations in hotels and apartments had become so common that experts couldn't recall a time when they weren't a problem. People hated being bitten in the night by these pesky bloodsuckers hiding in mattresses, but the bugs seemed impossible to wipe out.

Then everything changed in 1939, when a Swiss chemist named Paul Hermann Muller discovered the pesticide DDT, which proved stunningly effective at killing insects. For decades thereafter, DDT and other chemicals helped keep America's homes and hotels bedbug-free.

But it didn't last. Since 2000, a new strain of pesticide-resistant bedbugs has been popping up in the US. In 2009, there were 11,000 reported complaints in New York City alone. In New Jersey, a Rutgers study found, fully 1 in 8 low-income apartments had infestations, with bugs hiding in sofas, beds, and tiny cracks in the wall. Many residents don't realize anything's amiss until they wake up in the night with strange bites and rashes. By then, the unwelcome guests can be tough to get rid of.

One of the best recent books about bedbugs is Brooke Borel’s Infested: How the Bed Bug Infiltrated Our Bedroom and Took Over the World (the book was partially funded by the Alfred Sloan Foundation). Last year, I called Borel, a science journalist, to hear more about how bedbugs made a comeback, why they’re so tenacious, and whether we might ever get rid of them again.

Brad Plumer: I’d half assumed bedbugs were a very recent phenomenon, so it was fascinating to see that even the ancient Egyptians were trying to cast spells to ward them off.

Brooke Borel: Yeah, one thing that struck me were the similarities through history. When the bedbug resurgence happened in the last 15 years, we had all these newspaper articles saying, "Oh my god, they’re in the movie theaters, they're in this place, in that place." But that’s always been the case.

You can go back and read descriptions of old beds with jars around the legs that contained paraffin to ward off bedbugs. That’s just an old-school version of these little traps you can buy today to put under your bed. It’s an old story that’s been repeating itself forever.

BP: There was this 60-year period after World War II where we’d vanquished bedbugs. How did that happen?

BB: A big part of that story happened in 1939, when a Swiss chemist [Paul Hermann Müller] discovered the insecticidal properties of DDT. These were the first synthetic insecticides, and they were way more effective than the natural botanicals or elemental poisons we had been using previously.

Most insects had never experienced this type of poison before — and they were very vulnerable to it. So we were able to knock bedbug numbers down. One key thing about DDT is that it leaves a residue on surfaces for a long time: months, maybe even a year. That was especially effective against bedbugs, because they hide in cracks either during the day or whenever you’re not there to provide food. Earlier sprays might have dissipated or not gotten down into the cracks where the bedbugs were. But DDT leaves a residue, and bedbugs would walk through it in order to come eat.

There might have been other factors in knocking down bedbug numbers, too. Some experts point to different housekeeping practices that emerged after World War II — people were using vacuum cleaners more, and so on. That’s more anecdotal than anything else. Or in the United Kingdom, they were able to reduce bedbug numbers before the war, in the 1930s, because they completely tore down all these tenement buildings and rebuilt them.

BP: So how did bedbugs make a comeback? It wasn't simply because we banned DDT in the 1970s, was it?

BB: No. Some people still say the only reason we have bedbugs now is because we banned DDT [after concerns about its threat to wildlife]. But that’s just not true. We would’ve had this problem regardless of the ban. The bigger problem is that bedbugs were becoming resistant to DDT, and that was starting to happen way before the ban occurred.

DDT and other pesticides work on the nervous system of insects — often by screwing with their ion channels and leaving them open so that it fries the nervous system. These new resistant bedbugs were essentially able to close that channel again, so that didn’t happen.

BP: Okay, so some bedbugs evolved resistance to DDT. But how did they become so widespread?

BB: The idea is that pockets of resistant bedbugs evolved somewhere in the world, probably in more than one place. Then in the 1980s and 1990s, you have this huge increase in air travel both domestically and internationally — it got cheaper through the deregulation of airlines in the US and a set of new treaties in the 1990s. That probably helped spread these resistant bedbugs.

The question we still don’t know is where, exactly, the resistant bedbugs came from. One hypothesis is that it started in Eastern Europe. There’s also the idea that resistant bedbugs came from somewhere in Africa because of the use of pyrethroid-impregnated mosquito nets. I think that’s pretty compelling, too. [Pyrethroids are another pesticide that works by preventing the sodium channels of insects from closing.]

BP: So what is it that makes bedbugs so tenacious and hard to kill? Is it just this pesticide resistance?

BB: I think it’s the combination of so many things. They're cryptic insects, and they hide during the day, which makes them hard to detect with the human eye.

But the resistance is definitely a problem. Bedbugs have what’s called a knockdown resistance — it’s the same genetic mutation that gives them resistance to DDT. Separately, there are enzymes called P450s that break down the insecticides more quickly, so that they’re not as toxic to insects. There’s also research that some insects may be growing thicker exoskeletons, making it tougher for insecticides to penetrate.

There are other factors, too. Some people aren’t allergic to them, so they might catch the problem only far later, when it’s become a really bad infestation. Also, bedbugs can spread very easily in cities — because to get rid of them you have to work with other people sharing living space or sharing walls. That can be incredibly difficult.

There’s also a lot of shame involved in having bedbugs. And it’s expensive to get rid of them. So people might initially try to hide the fact that they have an infestation —until it gets worse and worse, and then it’s spilling over to neighbors.

BP: You mention in the book that you’ve experienced bedbug attacks several times. What is it that makes them so hellish?

BB: Before I answer that, I will say the reason I think I’ve encountered them so often is that I’m really, really allergic. Like in this Chicago hotel [where, in the book, she gets bitten], I was staying with a friend, and he didn’t get any bites. But he just might not have been allergic. A lot of people might sleep in beds with bedbugs and not notice at all.

Now, on the psychological part, probably any psychiatrist who has dealt with someone with bedbugs will tell you the same thing.

There is something about the fact that your bedroom is your sanctuary, and you’re also the most vulnerable in your bed, because you’re sleeping. You really don’t get much more vulnerable than that; you’re literally paralyzed. And to have something that’s hiding that you can’t see that comes out and attacks you in your sanctuary, that is just really psychological difficult.

BP: Why can’t we just invent a new chemical or insecticide to kill these bedbugs?

BB: It’s a pipeline problem, just like the discovery of antibiotics or other drugs or other insecticides. It gets increasingly difficult to find the right chemicals and figure out whether they’re safe enough for us to use.

Bedbugs are especially difficult, because they live in our bedroom, and that’s one of the places we want to be especially careful when it comes to applying insecticides. So that’s part of the issue there.

It’s also incredibly expensive to research and develop the ingredients that go into an insecticide. The estimate for pesticides is something like $256 million per active ingredient over a period of around a decade. And even though bedbugs seem like a big problem, and it seems like you could make money making a bedbug insecticide, it’s not anything compared to the amount of insecticides we use in agriculture. So it’s not necessarily a major focus of the chemical companies.

BP: So what are the best ideas experts have come up with for getting rid of bedbugs?

BB: Keep in mind that there’s a caveat for anything I could possibly say here. I do think heat treatments are very helpful — bedbugs don’t seem to be developing a resistance to those. Basically you heat a room to a certain temperature, and it kills the bugs and the eggs, without chemicals involved.

The caveats, though, are that this is expensive; it can cost thousands of dollars. It’s not necessarily the best approach in an apartment building, because if you only treat one unit, and the neighbors have bedbugs and aren’t taking care of the problem, then you’ve probably wasted that money, because the bedbugs are going to come back.

Then the other problem is that people have been hearing about this and trying to do their own heat treatments. They’ll use a space heater or something inappropriate, and their houses will catch fire. So it’s not for everyone.

BP: You did a lot of reporting on the multimillion-dollar industry that’s sprung up around controlling bedbugs. And you seemed to come away skeptical. Why?

BB: I think that especially in the United States, we’re still in this Wild West era for bedbug control. There are some people who really believe in their products, but their products are bad. You could walk into a store and see a product that says, "Kills bedbugs on contact." To a consumer, that sounds great, but all that means is you have to spray it directly on the bedbug. But bedbugs are often hiding, so that’s not necessarily helpful.

There’s a lot of opportunity to take advantage of people’s fears. Even the Federal Trade Commission has caught wind of this — they had two cases against two companies against products advertised as all-natural contact killers, and they said, "You can’t advertise like this."

BP: Having written the book, what advice would you give for someone who discovered bedbugs in their room?

BB: As far as the psychological stuff goes, I would say it’s going to suck — but don’t panic!

In every city and state, there’s a hodgepodge of rules for who’s responsible financially for a bedbug infestation. So the first step is getting educated on that. If you do rent, your landlord may be legally required to pay for bedbug treatments.

As far as actual treatments go … I have a little section in the book where I say what I would do. It’s not going to be right for every person. Because I’m so allergic, I’d know pretty quickly if I did have bedbugs. So before calling an exterminator, I would try to do all my laundry, do a search and see if I could find the bedbugs and where they’re coming from, clean up, and then see if I was still getting bites. But that’s mainly because I’d be able to tell easily if I was still getting bitten.

But that’s not necessarily right for everyone, and I don’t recommend that for each person. For the most part, I’d suggest people call a professional — though it can be daunting to figure out who’s good.

BP: Do we know if the bedbug problem is getting worse in the United States?

BB: It’s a little tough to say. In general, I don’t think the problem’s getting better; I don’t think there are fewer bugs. I do think people are not freaking out about them as much and are more knowledgeable on how to deal with them.

There’s a survey by the National Pest Management Association, where they interview pest-control people from all over the world and ask how many bedbug cases they had in the last year. And those numbers have continued to rise. Then again, that’s an industry group, and they’ve been making money out of this.

It also really depends on the city. I’m working on an essay about bedbugs in New York City, where numbers show that 311 calls about bedbugs are going down, but those numbers can be deceiving [since a lot of people don’t necessarily make 311 calls when they have bedbugs].

BP: You interviewed a lot of scientists for the book — I loved all the pictures of researchers who raise bedbugs for study by feeding them on their own arms.

BB: Some people still do that, though for a lot of these bedbug research labs they have way too many bugs to be able to do that. One of the fascinating things I learned was that it took a long time for scientists to figure out how best to keep bedbugs alive in the lab, given that they’re so hard to kill in the wild.

This interview has been lightly edited for length and clarity.

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