Bedbug sprays sold for residential use in neighborhood stores rarely eradicate or prevent bedbugs. Credit: Amy Maxmen
In April I moved from one bedbug infested district of Brooklyn to one infested worse. With 550 complaints filed in the bedbug registry in 2008, Bushwick, my new neighborhood, surpassed Central Harlem in Manhattan, Astoria in Queens, and University Heights in the Bronx. At every hardware and grocery store on the surrounding blocks, I eyed the array of bedbug sprays for sale beside the cash register. And had I not talked to experts while writing this blog post, I would have bought them as a preventative measure.
Among other misguided beliefs, the myth of bedbug spray seems to worry scientists and public health authorities the most. So I’ll start there.
DIY pesticides don’t work.
During the last 50 years, bedbugs have largely become biologically resistant to the pesticides sold at your corner store, namely pyrethroids and pyrethrins. DDT targets the same site as pyrethroids do, shedding doubts on claims that lifting the EPA’s ban on this dangerous chemical would curb the current bedbug resurgence. Spraying pyrethroids or pyrethrins directly on a resistant bedbug at close range may in fact kill the pest, but there’s little chance of hitting each individual insect, as armies of the sesame-seed sized bugs hide in the teeniest crevices.
"Hair spray, Windex, spearmint or eucalyptus oil will kill bedbugs at a close range too," says Coby Schal, an urban entomologist at North Carolina State University in Raleigh. "But I’m not advocating those approaches because bedbugs can walk right over these sprays." Although the insect repellent DEET is not a pyrethroid or pyrethrin, Schal says it won’t deter a starving bed bug from seeking out human blood. Instead, repellants and sprays encourage the bugs to explore unsprayed territory, like your living room or your neighbor’s flat.
Young and adult bedbugs fat after a blood meal. The brown spots are fecal smears of digested blood. Credit: Benoit Guenard
Pesticide resistance provides tremendous evidence for evolution by natural selection. A mutation in a gene encoding a protein in bedbugs’ nerve cells allows the cells to resist the lethal damage inflicted by pyrethroid and pyrethrins. With each spray, bedbugs with the mutation out-live their non-resistant pals and survive to produce resistant offspring. Incidentally, cockroaches have mutations in this protein, too. If it weren’t for poisoned bait, we might have a hefty cockroach problem on our hands, says Schal. At the moment, he is studying what attracts bedbugs to human blood. If this compound can be identified and mimicked, bedbugs might be baited, too.
Nonetheless, pyrethroid and pyrethrin sprays sell fast. And so do "bug bombs," cans of pesticide (typically pyrethroids) that release their contents at once. (One report describes a man blowing out the walls of his apartment by setting off the bug bomb near a gas stove with the pilot lights on—aerosol ignites.) These bombs fall in vain. Even if pyrethroids still worked, the bombs rarely send pesticide into cracks and voids where bedbugs dwell (1).
Worse yet, misuse of these sprays may lead to digestive problems, skin irritation, and may worsen asthma and allergies (1). "People think if you can buy a pesticide at a supermarket it can’t be dangerous, so they use them like mad when in fact almost none of these chemicals have been tested on humans," says Stephanie Chalupka, an environmental and occupational health expert in Massachusetts at Worcester State College and Harvard School of Public Health in Boston. "I think the public health community could do a better job of getting out information on what is useful and safe, and what may put kids at risk." Chalupka says she’s particularly concerned for pregnant women and their developing babies. "All sorts of compounds can get to the developing fetus, which is at a very vulnerable state as its organs and systems are forming."
Not all bugs are bedbugs.
Timothy Wong of M&M Pest Control in New York says 70 percent of the time, residents who call his company turn out to be bedbug-free. Mosquitoes, spiders and fleas leave itchy bites, too, and various other insects occupy our dwellings. Common bedbugs (Cimex lectularius) are reddish-brown and range from the size of a poppy seed to the size of a short grain of rice, depending on their age. Clumps of 10 to 50 white eggs, about the size of a pinhead, may be found in the vicinity of the bugs.
Bedbugs living on a mattress. Credit: Jung Kim and Rick Santangelo
To find bedbugs, check creases and seems in your mattress and box spring, behind the headboard, between couch cushions, under rugs, in nightstand drawers, under loose wallpaper, and cracks in plaster. Sometimes bedbugs leave behind bloodstains—pinprick-size droplets not to be confused with the rectangular feces left by cockroaches.
Clean or messy, bedbugs don’t discriminate.
"We’ve had calls from residents in filthy places and calls from residents who live on Park Avenue with full-time housekeepers," says Janet Friedman of Bed Bug Busters NY (a company of actors, singers and stage managers who prep apartments for exterminators on the side). Don’t be fooled by clean hotels either, Friedman warns. After returning home from vacation, she recommends tossing all clothing into the dryer for 30 minutes on high to kill any blood-sucking hitchhikers.
Metal and plastic harbor bedbugs.
Although bedbugs prefer wood with its numerous crooks and crannies, metal and plastic furniture or items often contain tiny hiding spots as well, particularly if there are parts with open tubes. If you simply must buy an item at a second-hand store, Schal recommends putting it in the freezer if it fits. If not, covering larger items like furniture with a garbage bag and placing them in the sun all day should bake any critters.
Bedbugs travel stealthily.
Bedbugs can walk from one apartment to the next through water pipes or electrical, heat, and phone line conduits. To explore this thrilling possibility, check out light fixtures, electrical switch plates, and hidden spots near the sink and bathtub. Although increased travel has been blamed for the bedbug resurgence, the pests also seem adept to exploring your neighborhood on their own.
Bedbugs hiding in a screw hole on a plastic desk chair. Credit: Louis N Sorkin, BCE, Entsult Associates, Inc.
Another of Coby Schal’s projects involves tracing bedbug migration by isolating genetic markers from the bugs and asking whether multiple infestations on a city block result from a single colony of critters expanding their territory, or from numerous invasions by different bedbug populations hitchhiking on various residents.
Bedbugs don’t transmit disease.
Bedbugs aren’t lazy.
Don’t be fooled, moving to the couch for a solid night of rest will only encourage bedbugs to spread into the living room.
The bedbug explosion is real.
According to the National Pest Management Association, 95 percent of pest professionals reported treating bedbugs in the past year, up from 25 percent in 2000. Titles of scientific articles published this year read: "Bedbugs: The Worldwide Renaissance of an Old Partner of Humankind," "Easing Bedbug Anxiety: What You Need to Know about the Recent Bedbug Resurgence" and "They Only Come Out at Night: Bedbugs and Their Alarming Resurgence." Finally, hip graphic designers have captured the trend—Christian Swinehart created a stylish interactive map depicting the growing infestation in the Big Apple.
Misinformation exacerbates the resurgence. As Wong explains, "The problem is people are fearful and when they panic, they employ all sorts of methods that make the situation worse." Unfortunately, this trend may continue, as local health departments are ill-equipped to handle pest outbreaks. In a 2007 survey 74 percent of local health departments reported that they did not have sufficient numbers of public health workers to staff their vector control units (2). "There’s been a steady erosion of pest management capacity at the state and local level," says Michael Herring, senior environmental health scientist at the U.S. Centers for Disease Control in Atlanta. "A lot of people call on their local health department when they have pest problems, especially if they don’t have money for an exterminator," he says, but without a vector control program, a department has little ability to respond quickly to calls and to spread the message about integrated pest management techniques.
In sum, if you’ve decided to live in a neighborhood like mine, follow the simple tips above and hope for the best. If that doesn’t pan out, call a professional.
1. Environmental Health Perspectives’ "Invasion of the Bedbugs"
2. CDC’s "Where have all the vector control programs gone?"
About the Author: Amy Maxmen is a freelance science writer based in New York. She received her PhD in Evolutionary Biology from Harvard in 2006.
The views expressed are those of the author and are not necessarily those of Scientific American.
Note: original text stated that DDT "falls into the pyrethroid group". It does not, though it targets the same site as pyrethroids do. This error has now been corrected in the text.