October 19, 2026, 9:28 am | Read time: 6 minutes
Bedbugs are considered persistent pests that spread in homes and are difficult to eliminate. But ironically, they seem to fear something quite ordinary. New research now reveals what seriously affects these insects. The discovery could even impact pest control, as PETBOOK editor and biologist Saskia Schneider explains.
Bedbugs Fear Something Everyone Has at Home
Bedbugs send shivers down many people’s spines–and rightly so. Not only do these insects crawl under the covers at night to suck blood, but they’re also hard to get rid of. If you discover an infestation, you need to call an exterminator to professionally combat the pests–using strong poison.
Now a new study shows: There might be an easier way. Researchers have found something that bedbugs seem to fear, and everyone has it at home: water!1
Study Documents Bedbugs’ Aversion to Water for the First Time
Yes, you read that right. Bedbugs don’t seem to like getting wet feet, as researchers at the University of California, Riverside (UCR) found. They describe for the first time a clear aversion of bedbugs to water and damp surfaces. The results were published in the journal “Journal of Ethology.”
Entomologist Dong-Hwan Choe, a professor at UCR and co-author of the study, sees a plausible anatomical explanation for this: Bedbugs have extremely flat bodies and small breathing openings–called spiracles–on the sides of their abdomen.
Water “Sticks” to Bedbugs
“When they physically come into contact with water, they get stuck on its surface, blocking their breathing openings,” Choe is quoted in the science magazine “Phys.Org.”
Sticking to water? Yes, it’s possible–at least if you’re as tiny as a bedbug. Because then the surface tension of water has a completely different physical effect than on larger bodies.
Adhesion Force Likely Causes Avoidance Behavior
This is due to the so-called surface tension, which arises from the special charge of water molecules. You might know the phenomenon: A full glass of water can be filled beyond the rim. The molecules “stick” to each other and hold together–until the force (in this case, gravity) becomes too great and the glass overflows.
This “sticking together” of molecules is referred to in physics as cohesion force. But it works not only among the molecules but also between water molecules and surfaces of any kind, which physicists then call adhesion force. And this could be why bedbugs fear water. When a drop touches the bug’s body, it “sticks” to it. But why is this a problem?
Bedbugs Could Drown from Tiny Drops
Unlike us, insects don’t breathe through a mouth and lungs but by actively pumping air into their bodies with their abdomen. This air enters the insect’s tracheal system through spiracles. These breathing openings are located on the sides of the abdomen–very close to the ground.
If water is on the ground and touches the bug’s abdomen, the droplets can cover these breathing openings. The bedbugs would then have no chance to remove them and risk suffocation–at least that’s the researchers’ theory.
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Accidental Observation in the Lab
The insight came rather accidentally in Choe’s lab. Bedbug colonies are usually kept in containers there. For feeding, researchers attach an artificial feeder to the top of the containers. The bugs crawl up and pierce their mouthparts through a membrane to take in blood.
One day, however, this membrane was slightly damaged, causing blood to leak and soak the paper in the container, which served as the bugs’ substrate. “I thought the bedbugs would like to drink the blood from the paper,” Choe reports in “Phys.Org.” “But what I saw was quite different. They actively avoided the part of the paper that became wet with blood. They didn’t even want to go near the damp areas.”
Experiments with Water Confirm Aversion
To verify the observation, the researchers additionally moistened the paper with water. The insects consistently avoided these wet areas as well. This prompted further experiments.
Postdoctoral researcher Jorge Bustamante from Choe’s team then developed an experimental design using a special infrared camera with a magnifying lens. Because, as Choe explains in “Phys.Org,” observing bedbugs isn’t easy. Especially the young stages are tiny–just two millimeters in size.
Using video analysis software, Bustamante was able to evaluate color differences between insects and background to accurately capture movement patterns. Speed and distance with which the bugs moved away from wet surfaces were examined. He also analyzed differences in gender and age.
Young Bedbugs React Particularly Sensitively
The result: All bedbugs–male and female, older and younger–avoided wet surfaces. It was also noticeable that the bugs moved away from water faster than they approached it.
Especially young, smaller bedbugs showed a pronounced reaction. They made a quick abrupt turn as soon as they approached a damp spot. This suggests that younger bugs are more sensitive to moisture than older ones. Given that they are significantly smaller, this makes sense, as the surface tension of water would have an even greater effect on them than on larger, adult bugs.
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Implications for Pest Control
But does this mean you can simply get rid of bedbugs by spraying bed frames and walls with water? To answer this question, more research is needed. However, Choe and his colleagues already agree that the results of their work will have practical implications.
Especially companies developing or testing water-based insecticide sprays should consider this behavior, according to the researchers. Since bedbugs actively avoid wet areas, they could leave treated areas and temporarily retreat to other parts of an infested property–with consequences, as Choe warns: “If the insecticides don’t kill the bedbugs immediately, they leave the treated areas and spread elsewhere.”
How to effectively combat bedbugs in your home can be found with the colleagues at myHOMEBOOK: How to identify and combat bedbugs
A Simple Tip if You Suspect Bedbugs
For those who fear bedbugs might be on their clothing or body, Choe has a tip: “Take a bath. That will solve the problem,” he said. “Of course, bedbugs in the room or on the bed will require other approaches.” But at least it’s not necessary to treat clothing or skin and hair with pesticides, as is done with head lice–water is sufficient here.