Preface
“Do bed bugs smell?” is surprisingly a pretty common question. I have actually had two of my customers tell me that they love the smell of crushed bed bugs. I was bit shocked and couldn’t help but laugh. But it got me thinking, maybe it is a question worth addressing.
Do bed bugs smell and what causes it
Yes, very highly concentrated bed bug infestations can release a noticeable odour. People who have smelt it often describe its as either sweet, similar to the smell of spoiled raspberries, or damp towels. As for my customers who smelled the individual crushed bed bugs, they described it as a rusty scent. My understanding is that, the rusty smell likely comes from the blood inside the bed bugs.
Odour from bed bug infestations is likely to be present when shed skins, dried blood, egg clusters, fecal matter and large colonies of bed bugs are all present in tight crack or crevices. The smell is most noticeable when the infestation is very heavy and concentrated in a small room. In addition, a smell can often be detected from the chemicals bed bugs release. These chemicals are called pheromones and bed bugs release them to communicate.
Can we rely on the smell to detect an infestation
It is important to note that small or early infestations do not produce any scent at all that a human can notice. Even if a detectable odour is present, many people are not sensitive to it or become used to it over time. In addition, factors like heat, humidity, ventilation, and how often people sleep in the respective room, all effect the scent. Therefore, there is no reliable way to separate an odour caused by a bed bug infestation from another, especially by humans.
Many pest control companies use trained Canines to detect bed bug infestations based on odours alone and believe that this is a very accurate method. However, a study titled Accuracy of Trained Canines for Detecting Bed Bugs (Hemiptera: Cimicidae) by Richard Cooper, Changlu Wang, and Narinderpal Singh revealed that “In three separate experiments, the mean (min, max) detection rate was 44 (10-100)% and mean false-positive rate was 15 (0-57)%.”
This is why relying on smell alone is very risky and not a method useful to detect any type of bed bug activity.
Final thoughts
Bed bug odour is real, but it cannot be relied on to detect an infestation. The only way to know for sure is to find physical signs or bring in an expert entomologist. And the only way to remove any odour from your home is to remove what is causing it. Thus, a bed bug odour fades after a professional treatment has successfully eliminated the infestation.
