After an invasion of insects, most people want to put the creepy-crawlies out of mind. But when science writer Brooke Borel suffered three bed bug infestations in New York City, she found herself fascinated by the little bloodsuckers. In her new book, Infested: How the Bed Bug Infiltrated Our Bedrooms and Took Over the World, Borel examines the science, history, and psychology of one of our hardiest and most intimate pests. We got a chance recently to chat with her about the book:
(This interview has been lightly edited for length and clarity).
World Science Festival: The basic story I’ve always heard is that after the pesticide DDT was banned, bed bugs came roaring back. So where were they hiding out all this time?
Brooke Borel: The answer is not clear yet. But the basic story is this: We have a really long history with bed bugs that goes back hundreds of thousands of years. Around World War II, a chemist in Switzerland found the insecticidal properties of DDT, and after the war it became commercialized. DDT happens to be very effective against bed bugs because it leaves a residue on surfaces. Bed bugs hide when they’re not feeding, so to kill them with chemicals, having a residue that they walk through is really helpful.
However, there were already pockets of bed bugs resistant to DDT all over the world within a few years of the first use—one of the early ones was in an army barracks in Hawaii; there were some in Korea, Israel, Ohio. Where they spilled over from during this more recent resurgence, that’s a matter of debate. Some scientists think they might have spilled over from multiple locations simultaneously.
WSF: You mentioned in the book a theory that they were hiding out on poultry farms?
Borel: Yes. The species that feeds on us in the United States, Cimex lectularius, can feed on other animals. Scientists raising them in the lab have fed them on everything from chicken blood to rabbit blood. There are also a lot of different species of bed bugs that are more adapted to live on different animals, usually birds or bats.
So it’s possible that bed bugs were staying on poultry farms, but the genetic analysis suggests that’s not the case. It seems more likely that they were feeding on people in different parts of the world and just spilled over.
WSF: How does a bed bug feed?
Borel: It has this thin proboscis, and that goes into the skin. The proboscis is really acrobatic, it can move around at up to a 90-degree angle looking for a blood vessel. Once it hits the blood vessel, the pressure difference between the vessel and the bed bug’s body makes it poof up. Some insects lap blood, but the bed bug is filling up directly.
WSF: Why do we seem to find bed bugs so much scarier than other pests?
WSF: Were you surprised by anything you learned while researching the book?
Borel: One thing I find really fascinating is the researchers who are looking at the genetics of bed bugs that feed on people and then comparing them with members of the same species that live with bats in Eastern Europe. Scientists think that bed bugs originated hundreds of thousands of years ago, living in caves with bats. Some of our hominin ancestors went into those caves, some of the bugs started feeding on them, and eventually hitchhiked out and followed us. The rest is history.
When I started the book, I was always under the impression that the bed bug living on bats was some other species. But the bugs feeding on people and the bugs living with bats in caves—also in church attics, apartment attics, what have you—they’re the same species, maybe in the process of splitting into two separate species. So the bed bug might be an interesting model for studying evolution and understanding how species diverge onto two different hosts.
WSF: Are there any new bed bug control methods that seem like winners to you?
Borel: There’s no one single thing that stands out. The pest control people have a philosophy called integrated pest management. They’re trying to minimize insecticide use while throwing in as many different tactics as possible to get rid of an infestation.
I do think one good approach is heat treatments. They work very well if they’re done correctly, but they can cost thousands of dollars and they’re not ideal for apartment buildings and so forth. There are some things that do clearly work well in certain circumstances, but there’s always some “but”—it’s expensive, it’s not as good in this situation, or people aren’t trained enough to do it well.
WSF: Any advice for people suffering through an infestation?
Borel: Just know that it will eventually end. There can be some terrible stories, especially if people are renting from a landlord who isn’t very helpful. But bed bugs at this point aren’t known to spread disease. There still needs to be more research, but this is something scientists have been looking at for decades and thus far there’s no strong evidence that they can spread disease between people.
Also, people can get quite anxious just at the thought of picking up bed bugs from a hotel room or a movie theatre. I don’t think people should stop doing things that they like because of fear of picking up bed bugs. Just be aware that they exist, and be mindful of, say, where you put your suitcase at a hotel. There are ways you can minimize the possibilities of bringing them home.
The following excerpt from Infested sheds light on efforts to develop the next generation of anti-bed bug treatments:
“Modern bed bug traps face the same problem as all those that came before: in order to work, bed bugs must walk through them. Even when they do, it proves the existence of the bugs in a room, but it doesn’t mean it has trapped or killed them all. This requires an inescapable mode of death. Since synthetic chemical killers are expensive and elusive, some scientists have looked for other ways to poison the insects.
“Scientists from Penn State University think the answer may lie in the fungus Beauveria bassiana, which lives in soil throughout the world. B. bassiana is a biopesticide—a natural insecticide found in living things including animals, bacteria, and plants, or from minerals or oils. The fungus’s fine white dusty spores have a natural affinity for fatty surfaces. When certain insects come into contact with the spores, either through contaminated soil or other infected insects, the spores stick to the outermost layer of the waxy exoskeleton. The moisture on the insect’s body allows the spores to sprout, and they penetrate into the exoskeleton. From there, the fungus spreads, blooming in the insect’s circulatory system and clogging it.
“In the Penn State tests, the scientists sprayed various surfaces, including smooth printer paper and textured jersey knit, with a milky mixture of the fungus and dropped bed bugs on top. Both Harlan bugs and a strain collected form the field died within three to six days. But to make it as a product, the fungus would have to pass EPA requirements for biopesticides, which are just as stringent as those for synthetic pesticides. Here, the agency is concerned with not only toxicity, but also hypersensitivity and infectivity. This means the agency wants proof that the fungus won’t irritate a person’s skin or pierce it and bloom inside the blood.”
From Infested: How the Bed Bug Infiltrated Our Bedrooms and Took Over the World, by Brooke Borel. Copyright 2015 by Brooke Borel. Published by the University of Chicago Press with additional support from the Alfred P. Sloan Foundation. All rights reserved.