An accidental laboratory discovery has revealed that bedbugs are terrified of water and moisture, a finding that could lead to new strategies for controlling the spread of these invasive insects. The common bedbug, Cimex lectularius, is a blood-sucking pest that can quickly establish itself in homes and is notoriously difficult to eliminate.
Researchers have observed a global resurgence of bedbugs over the past 20 years, largely due to their developing resistance to chemical pesticides. This has prompted scientists to study their behaviour more closely to improve control methods. The new study, published in the Journal of Ethology, shows that bedbugs actively avoid water and wet surfaces, a behaviour previously unknown.
The finding fits with the physical structure of bedbugs, which have flat bodies and small breathing openings called spiracles along their abdomen. 'If they physically contact a body of water, they’ll get stuck to its surface, blocking their respiratory openings,' explained Dr Dong Hwan Choe, an entomologist at the University of California, Riverside and an author of the study. 'Due to its strong adhesive power, water could be very dangerous from a bedbug’s perspective.'
The discovery was made accidentally during routine lab work. Researchers were maintaining bedbug colonies in small vials with an artificial feeder filled with blood placed on top. When a vial membrane was slightly damaged, blood leaked onto a paper inside the vial. 'I thought the bedbugs would be happy to drink the blood from the paper,' Dr Choe said. 'But what I saw was very different. They were actively avoiding the part of the paper that became wet with blood.'
Further experiments confirmed that all bedbugs—male, female, young, and old—avoided wet surfaces. The pests often retreated from wet areas faster than they approached them, sometimes performing 'rapid U turns'. The researchers suggest this behaviour could influence infestation control strategies. 'Take a bath. It’ll solve the problem,' Dr Choe said, though he noted that bedbugs in the room or on the bed would require different approaches.
