Why have bed bugs become so difficult to control? We can only blame ourselves

As panicked headlines around the world will testify, bed bugs have made a big comeback. While it’s fair to say the widely loathed pests never went away — they are easily transmitted from one person or household to another, and notoriously difficult to get rid of — experts say that over the past few decades bed bugs have become increasingly resistant to the insecticides generally used to kill them. The result has been a major resurgence of bed bug infestations around the world, made worse by economic inequality and the lack of consistent public health policy to address the issue.

Aimée Code, the pesticide program director at the invertebrate advocacy group The Xerces Society, wants you to know something about bed bugs: They should not ruin your impression of other insects.

"Bed bugs are definitely an insect that make people squeamish, and for good reason: they are a parasite that can be picked up unexpectedly and are hard to get rid of," Code told Salon. But she added that "The vast majority of insects (and other invertebrates) add tremendous value."

Code proceeded to list some of the countless benefits that humans derive from insects, from feeding birds and cleaning water to pollinating food and controlling populations of harmless organisms. "Even bed bugs, which are clearly a pest in our homes, provide food to spiders and other wildlife."

It is understandable why Code seems defensive of insects overall when discussing bed bugs. At the time of this writing, there is a global resurgence of bed bugs thanks to two species: the common bed bug Cimex lectularius and the tropical bed bug Cimex hemipterus. The wingless, pill-shaped insects feed on mammalian blood and, as indicated by their name, are notorious for infesting human dwellings. This includes bedrooms but is not limited to them, as a recent reported infestation at the MSNBC office in New York City indicates.

There have also been bed bug resurgences from France and the United Kingdom to Australia and Japan. When bed bugs target a dwelling, the human residents can develop skin itchy bumps and rashes near the bug bites, as well as possible allergic reactions. People struggling with bed bug infestations can also experience mental health issues like anxiety, stress and (of course) insomnia.

Unfortunately, human activity is only making the problem worse. According to a 2023 study in the Annual Review of Entomology, the two most common forms of bed bugs have developed a resistance to common pesticides. Indeed, they are so resistant that many exterminators say people with bed bug infestations should not waste their time using their sprays — they're essentially useless anyway and you're just spreading a toxin that could spread to non-target insects.

There are other ways of controlling the pests, but Americans still spend a lot in an attempt to keep them at bay.

"The annual fiscal impact of bed bug infestation in the U.S. is estimated to be $1 billion," Chow-Yang Lee, a professor of urban entomology at the University of California, Riverside told Salon by email. "The number of inquiries about bed bugs to the Japan Pest Control Association increased tremendously from about 10 per year in 1995 to more than 300 per year in 2014."

Although Lee acknowledge that humanity has "made some progress in managing the present resurgence of bed bugs, the light at the end of the tunnel remains unseen." After reviewing how bed bugs mainly afflict people from low-income backgrounds who cannot afford expensive pest control methods, Lee concluded that because "infestations in low-income houses can become massive and serve as an insecticide-resistant bed bug reservoir for spread throughout the community," as a result "it is anticipated that bed bugs will continue to be a significant urban pest for many years to come. The world needs to think of bed bugs as a community problem, rather than as an individual issue."

Lee's reference to insecticide-resistant bed bug reservoirs reflects on one reason why they are flourishing: Their adaptation to pesticides meant to wipe them out.

"Insecticide resistance is likely the leading cause of the global resurgence of bed bugs over the last 25 years," Lee explained. "Insecticide resistance in bed bugs have been a major challenge to the pest management industry. Almost all the bed bug populations collected around the world showed resistance towards commonly used insecticides from the class of pyrethroids and neonicotinoids."

Want more health and science stories in your inbox? Subscribe to Salon's weekly newsletter Lab Notes.

Code echoed Lee's observation.

"Pesticides are often used as a first line of defense when a pest problem arises," Code told Salon. "That reliance on chemical management is in part why pests become resistant to pesticides." Indeed, pesticides had been so effective at killing all but the hardiest of bed bugs that some Americans were surprised when they returned, starting in the early 2000s. Now that those resistant bed bugs have survived and procreated, humans are the ones who must adapt.

"When control is needed there are options besides chemicals," Code explained. "Heat is an effective control for bed bugs (and a control technique to which they cannot become resistant). Some housing units have shifted to using heat both to kill existing bed bugs and to prevent new infestations."

One way to ensure to detect these bugs is setting a trap with dry ice overnight. The melting dry ice releases CO2, just like a breathing human, and attracts bed bugs.

Pesticides are not the only culprit in bed bugs' resurgence.

"We have almost 2 years of limited travel during the COVID-19 pandemic," Lee pointed out. "During this time, there were less movement of people and so bed bugs also have limited number of hosts." This caused their populations to temporarily subside, but once the pandemic ended, their numbers shot right back up.

"The recent increase in bed bug infestation around the world is likely due to increase in the number of human hosts, hence with blood meals, their populations increase massively within short period of time," Lee said. "Popular tourist locations in Europe and in Asia are seeing all time high of bed bug infestations. High movement of people also means bed bugs could hitch-hike from one to location to another very quickly."

Over the last five years, tropical bed bugs have been reported in various regions of Europe, including Central Europe, France, Sweden, Italy, Spain, Russia, Norway and more recently in South Korea.

Zachary DeVries, an urban entomologist at the University of Kentucky, perhaps best summed up the bottom line when it comes to humanity's future in dealing with bed bugs.

"Bed bugs are a major problem, but manageable by trained professionals," DeVries told Salon. "People should have a health respect for them and be vigilant when traveling, especially with spring break right around the corner. The best way to combat bed bugs is prevention, followed by early detection; if you can keep them out of catch them before they get established control is much easier."