Bed bugs around the world are developing resistance to insecticides, and infestations are making headlines. How do we deal with them?
France is currently in the grip of a bed bug invasion.
This year, in Paris, bed bugs have been reported in schools, trains, hospitals and cinemas. But the infestation has been gathering pace for some time. In 2020, an entire unit in a French hospital had to close after a patient was admitted carrying bed bugs. The decision to close the unit was taken after investigations using a sniffer dog revealed that four rooms were infested. The closure lasted 24 days, and cost approximately US$400,000 (£333,000) to treat.
Bed bugs are most active during a five-hour period overnight – between 12am and 5am. That’s no accident – we’re likely to be in deep sleep, and less likely to wake and interrupt feeding.
The insects hone in on sleeping humans with the help of two cues – carbon dioxide (CO2) emissions and body heat. The bugs can sense CO2 from around 3ft (0.9m) away, and body heat slightly closer.
However, you don’t have to be sleeping close to their borrows to be bitten – the bugs will wander several metres during the night in search of a host.
During feeding, bed bugs probe the skin with their mouthparts searching for blood-carrying capillaries, researchers at Virginia Tech in the US say.
A bed bug may not find a capillary with the first bite – meaning that victims may suffer several bites from the same bug during a feeding period.
Feeding takes between five and 10 minutes, before the bug retires to a crack to digest its meal. It may take up to a week before it needs to feed again.
Heating: Best way to kill Bedbugs!
Heating your house is also not something you should try at home.
“Don’t ever try to use heat yourself,” says Booth. “I’ve heard stories of people going to get propane heaters and setting their house on fire. It just doesn’t work. You’re more likely to kill yourself then do harm to the bed bugs.”
Some researchers are coming up with ways to lure bed bugs out of their hiding places so that they are more susceptible to pesticides. Students at Stockholm’s Royal Institute of Technology recently created a machine that can simulate human breathing. The idea is that the machine could act as bait to lure the bedbugs out of their nests, as research suggests that bedbugs are attracted to the carbon dioxide (CO2) that humans emit.
Bio pesticide: Second Best way to kill bedbugs!
Researchers are also developing natural-based biopesticides that insects are less able to evolve resistance to. In 2012, Nina Jenkins, an entomologist at Pennsylvania State University in the US, developed a formulation containing Beauveria bassiana, a natural and indigenous fungus that causes disease in insects, but is harmless to humans.
Unlike chemical pesticides, which require direct, long-term exposure to be lethal, the fungus spores are picked up by bedbugs when they walk across the sprayed surface. Once covered in the spores, the bugs spread them around by grooming themselves, and within 20 hours of exposure, the spores germinate and colonise their bodies. Jenkins has now formed a spin-out company to market the product.
“Bed bugs only need to contact the treated surface briefly to pick up the spores and become infected,” says Jenkins. “Exposed bed bugs also take the spores back to their hidden shelters, infecting other bed bugs in the population. This strategy works because bed bugs are ‘obligate blood feeders’ who must emerge from their hidden shelters to seek a blood meal.”