In 2004, Brooke Borel got bed bugs in New York. Then she experienced them again in 2009 — twice in two different apartments. Because of those experiences, which were part of a widespread bed bug resurgence in the US, Borel, a science journalist, decided to explore why the bugs were back. This excerpt is one of many stories from her new book: Infested: How the Bed Bug Infiltrated Our Bedrooms and Took Over the World.
In 1965 at the Limited War Laboratory in Aberdeen, Maryland, army entomologists were testing bed bugs for combat. The Vietnam War had escalated on the other side of the world, and the Vietcong were putting up a more impressive fight than the Americans and their allies had expected. The enemy's familiarity with the jungle made it easy to ambush US soldiers; the army was thus desperate to flush the guerillas out.
The Americans stripped the leafy jungle greens with Agent Orange and other defoliants so that the trees could no longer conceal an attack, and they trained German shepherds to sniff out hidden enemies sneaking through the ruined forest remains. But the researchers at Aberdeen thought that the bed bug might be a more versatile lookout. Compared to dogs, insects were easier to transport, required less care and attention, and needed no training.
Bed bugs are also naturally attracted to humans. The scientists wanted to exploit this tendency, whether in this species or a short list of other bloodsuckers, to see if they could detect the heat coming off of an enemy's body or the carbon dioxide from his breath. In addition to the bed bug, the contenders included an unnamed species of lice; Xenopsylla cheopis, the Oriental rat flea; Amblyomma americanum, the lone star tick; three mosquito species; and Triatoma infestans, the kissing bug and most infamous carrier of Chagas disease.
The scientists put each species through a series of tests to observe how the insects acted when a person was nearby and to see whether that action could be converted into a warning signal. Lice were ruled out early because their aimless crawls didn't change when a person was nearby. The fleas did notice the presence of a person, but they became so excited when they smelled a potential meal that they tapped like kernels of popcorn against a metal detection chamber and took too long to settle back down, which meant they were sensors that couldn't reset. The soft feet of the tick made no discernible noise even after the researchers hung weights from the arthropods' legs in hopes that the additional heft might audibly scrape across a detector's surface.
In tests on one species of mosquito, the insects responded by probing a screened, skin-like membrane, thinking it was food whenever the researchers wafted in a human scent. A phonograph pickup, the same device that captures the vibration from the strum of an electric guitar and converts it to an electrical signal, connected to the membrane and converted the action of each wishful bite so it resonated like a plucked guitar string. And the kissing bug, a distant cousin of the bed bug, made a raucous noise with each of its footsteps, which was promising.
Both adult and nymph bed bugs sprung to attention when a meal was nearby, but only the younger bugs reacted strongly enough in initial tests to warrant the construction of a complex sensor. The researchers made one from a coiled spring of piano wire connected to a phono pickup. Just as the mosquitoes bit the fake skin in their detector, the bed bug nymphs shimmied across the piano wire, triggered it, and produced a sound. But when the wires, the bugs, and the pickup were put in a portable container — a small mesh envelope — the sound was too muffled to hear. The intrepid scientists built a chamber of fine steel wool and put the bugs and the detector inside. This helped, but the device still was not good enough to be useful on the battlefield. None of the other insect finalists that the army entomologists tested worked out, either, and the project was abandoned.
That the bed bug was included in the Aberdeen research in the sixties was unusual — as the bed bug faded from homes and our collective memory, it also became less common in the laboratory. In the decades leading up to World War II, scientists had mainly tried to understand the bugs' basic biology, whether they were a health threat, and how to kill them. Both during and directly after the war, the research slanted toward pest control through experiments using DDT and other poisons.
Illustration of proposed insect ambush detector from the US Army. Credit: Clyde Barnhart, courtesy of the Aberdeen Proving Ground, Maryland.
By the late fifties, just after DDT's initial deluge, the scientists' interest dipped for about a decade, corresponding with the decimation of the bug. In the years that followed, what little research there was came from the developing world, where the pest was still a problem: countries in Africa and Asia, or institutions including the London School of Hygiene and Tropical Medicine, which often operated in those regions. Just a handful of studies were published each year. Many looked at the tropical bed bug rather than the common one, and most of the work focused on public health, pesticide effectiveness, or, as bed bugs evolved to withstand DDT and its cousins, pesticide resistance. The research on the latter grew in the decades following the war, for even DDT couldn't completely destroy what nature had perfected over millennia, and thus bed bugs hadn't disappeared entirely.
Four years after the Americans and the Brits added DDT to their wartime supply lists, scientists found bed bugs resistant to the insecticide in Pearl Harbour barracks. More resistant bed bugs soon showed up in Japan, Korea, Iran, Israel, French Guiana, and Columbus, Ohio. In 1958 James Busvine of the London School of Hygiene and Tropical Medicine showed DDT resistance in bed bugs as well as cross- resistance to several similar pesticides, including a tenfold increase in resistance to a common organic one called pyrethrin. In 1964 scientists tested bed bugs that had proven resistant five years prior but had not been exposed to any insecticides since. The bugs still defied the DDT.
Soon there was a long list of other insect and arachnid with an increasing immunity to DDT: lice, mosquitoes, house flies, fruit flies, cockroaches, ticks, and the tropical bed bug. In 1969 one entomology professor would write of the trend: "The events of the past 25 years have taught us that virtually any chemical control method we have devised for insects is eventually destined to become obsolete, and that insect control can never be static but must be in a dynamic state of constant evolution." In other words, in the race between chemical and insect, the insects always pull ahead.