Bed bug behaviour in public areas

A few years ago Richard Cooper et al published an excellent article entitled “Bed Bugs In Office Buildings : The Ultimate challenge.” The authors stated, in regard to public spaces, that “bed bug numbers tend to be low, increasing by periodic reintroductions rather than through reproduction.” In my own experience I would agree with that statement. Whenever I am asked to inspect a school, office, or other public area due to a bed bug finding I rarely find any evidence of bed bugs. When I speak with employees of other large public buildings that had a bed bug complaint an intense search for bugs by the exterminators found very few, if any, bugs.

Initially I found this finding very puzzling as a 6 month old infestation in a residential setting can easily result in thousands of bugs. But in the case of the Millenium Library there have been bugs dropped in that building for at least 6 years and yet there is little evidence of bugs. How can you have a 6 year old infestation and have an end result of very few bugs? The exterminator contracted to address those buildings might argue that it was their incredibly good work practices that should take the credit  but how could an exterminator address the millions of potentially infested books  as well as the hundred thousand square feet of space adequately  in just a few hours?  A library is an exterminator’s nightmare in terms of inspecting all potential harbourages.    It is obvious that an exterminator could, at best, address a very small percentage of the problem and the reason for the lack of bugs lies elsewhere.

One fascinating case I was involved in was a public school with teachers that taught part time at a small satellite school. The Satellite school regularly had students with bed bugs on their belongings and the issue was never addressed. Two teachers working at this little satellite school complained that they got bed bugs at home and they blamed the satellite school. I was asked to inspect this school that had regular introductions of bed bugs for at least two years with no exterminator input. I inspected the school (perhaps 2000 square feet in total) very carefully and found zero evidence of bed bugs. There was no exterminator involvement for two years and there was still no evidence of bugs!!

That brings me back to Richard Cooper’s article in which he argued that bed bugs “increase by periodic reintroductions rather than through reproduction.” This statement infers that bugs rarely reproduce in public settings. Why do the bugs not reproduce in public settings? I have a theory.

My bed bug starvation experiments clearly demonstrated that the bugs, when starved, become active in the presence of a host. I suggest the bugs that are dropped in a public setting initially hunker down in a corner somewhere waiting and searching for an appropriate sleeping host but when none is found they become desperate and climb the legs of hosts that are awake. I have also found that bed bugs are a bit clumsy when climbing down and prefer not to climb down. For example, in my experiments, bugs periodically tripped and fell off a rough plywood substrate when attempting to climb down. Bugs never fell off those substrates when climbing up. We also found that bed bugs could easily climb a varnished block of wood but then could not get off that block without falling off. I suggest that the bug’s feet are shaped like backward facing sharp hooks and are ideally suited for climbing. But when the bugs climb down the sharp hooks are facing the wrong way and the bugs become clumsy and prone to falling. In all the time I have spent watching bugs in my experimental pan I never noted a bug deliberately falling. The falls were always accidental. I suspect the starving bugs will climb the leg of a host but then find that the constant movement of the host does not allow the bug to climb off. The bugs hunker down behind a belt or pocket and leave the building with the new host. Therefore bugs in public buildings are imported and exported at roughly constant rates leaving the populations very low. This theory perfectly explains why the bugs do not reproduce in public buildings. It makes sense and fits the evidence perfectly. It even explains why those two teachers mentioned earlier had bed bugs in their homes. This theory also questions the value of exterminator input in public buildings.  Given the extreme difficulty of addressing the billions of potential harbourage areas in public settings the exterminator has little real impact on bed bug control.  It is the natural exportation of bugs that limits bug populations in public areas.

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