Bedbugs are small insects and suck human blood for their sustenance. They hide around beds in small cracks and crevices. Their existence can be identified by the presence of small bugs or tiny white eggs in the crevices and joints of furniture and mattresses. You might also locate mottled bedbug shells in these areas. A third sign of existence is the presence of tiny black spots on the mattress which are fecal matter, or red blood spots. And if you have itchy bites on your skin, then that is a clear sign. Unfortunately it is the fourth that provides people with the impetus to check their living areas for bugs, rather than the need to maintain hygiene by changing sheets.
The incidences of bedbugs have increased globally and one theory is that that visitors to countries where the hygiene levels are less stringent bring them back to their own country. The cost of cheap travel, both in terms of rail tickets and air flights, has enabled people to visit far-flung places. But one thing that has not been so apparent is how the bed bugs are carried back. It had been thought that bugs are more drawn to the presence of a human being – but surely they don’t piggyback on one across regions and continents?
The authors of a recent research into the matter have a new perspective of the matter. They believe that bugs are drawn to evidence of human presence, and not necessarily just to the presence of a human host. They believe that bed bugs, in places where hygiene is slightly lacking, collect in the dirty laundry of tourists and are then transported back to the tourists’ own location, from where they feed and multiply.
While this was an experimental study, the results are interesting because it had been previously thought that bed bugs prefer to be near sleeping people because they can sense blood.
The experiments leading to these results were conducted in two identical rooms.
Clothes which had been worn for three hours of daily human activity were taken from four volunteers. As a basis of comparison, clean clothes were also used. Both sets of clothes were placed into clean, cotton tote bags.
The rooms were identically set to 22 degrees Celsius, and the only difference was that one room had higher carbon dioxide levels than the other, to simulate the presence of a human being.
A sealed container with bed bugs in was placed in each room for 48 hours. After twenty four hours, when the carbon dioxide levels had settled, they were released.
In each room there were four clothing bags introduced – two containing soiled laundry and the other two containing clean laundry, presented in a way that mimicked the placement of clean and soiled clothes in a hotel room.
After a further 4 days, the number of bedbugs and their locations were recorded. The experiment was repeated six times and each experiment was preceded by a complete clean of the room with bleach.
The results between both rooms were similar, in that bed bugs gravitated towards the bags containing soiled clothes. The level of carbon dioxide was not a distinguishing factor in this instance, and the result suggested traces of human odour was enough to attract bed bugs. The physical presence of a human being was not necessary.
The carbon dioxide however did influence behaviour in that it encouraged more bed bugs to leave the container in the room with carbon dioxide.
In other words, the carbon dioxide levels in a room are enough to alert bed bugs to human presence, and traces of human odour in clothes are enough to attract them.
Why is this hypothesis useful to know? If you go to a place where the hygiene is suspect, then during the night when you are asleep, the bed bugs know you are present, and if they do not bite you, during the day they may come out and embed themselves in your dirty laundry. The researchers concluded that the management of holiday clothing could help you avoid bringing home bedbugs.
The simple way of protecting yourself against these pesky hitchhikers could just be to keep dirty laundry in sealable bags, such as those with a zip lock, so they cannot access it. Whether or not it means they will turn their attention to you during your holiday is a different matter, but at least it means you will avoid bringing the unwanted bugs back into your own home.
The study was carried out by researchers from the University of Sheffield and was funded by the Department of Animal & Plant Sciences within the same university.
More research of course is needed into the study. For example, if there were a pile of unwashed clothes while some was sleeping in the room, would the bugs gravitate towards the human or towards the clothes? It is more likely that they move for the human, but that kind of theory is difficult to test without willing volunteers!
Also, did the bugs in the room only head for the unwashed clothes because of the absence of a human, or did the proximity of the clothes to the container lull them into account the way they did? Also what is not accounted for are other factors by which bed bugs may be drawn to where they reside. Perhaps in the absence of a human being in the room, bed bugs would head for the next best alternative, which are clothes with trace human odours or skin cells, but perhaps with a human being in the room, bed bugs might rely on temperature differences to know where to zoom in on. In other words, instead of detecting human presence using carbon dioxide, they rely on the difference in temperature of the human body relative to its surroundings (the human body is at 36.9 degrees Celsius).
Carbon dioxide levels have been shown to influence mosquitoes and how they react but perhaps bed bugs rely on other cues.
There could be other factors that cannot or were not be be recreated in the same controlled environment of the experiment.
Ever wonder what it was like in the past centuries? Did people have to deal with bed bugs if they lived in the times of the Baroque ?
Nobody knows but one thing is for sure. Getting rid of bed bugs is a bothersome business but if you can prevent them getting in your home in the first place, all the better!