A new article in the Journal of Economic Entomology should have important implications for policy making—if we are smart enough as a society to appreciate the stakes.
Wang, C., K. Saltzmann, E. Chin, G. W. Bennett, T. Gibb. 2010. Characteristics of Cimex lectularius (Hemiptera: Cimicidae), Infestation and Dispersal in a High-Rise Apartment Building. Journal of Economic Entomology 103(1):172-177 DOI: 10.1603/EC09230
First let me get this out of the way. Check out this first sentence from the abstract:
Bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae), are a fast-growing urban pest of significant public health importance in the United States and many other countries.
Significant public health importance. I think of this phrase every day. May it one day mean what it says, yes?
Dr. Wang and colleagues studied a bed bug infestation in a 233-unit building for low-income elderly and disabled tenants in Indianapolis. The infestation is believed to have started with one tenant moving in, but it had already spread to more than 10 apartments by the time building management learned about it. Bed bugs spread in this building between 2006-2008 and a variety of treatments were tried, including educational efforts and treatments by the researchers themselves in 24 apartments from 2007-2008.
From December 2008 to April 2009 the researchers conducted inspections of apartments with reported infestations and interviewed the tenants. Bed bugs were counted and removed and Climbup Interceptors were installed. Adjacent apartments were then inspected and, not surprisingly, there were a number of apartments that could not be inspected. Apartments across the hall were also inspected:
After an apartment was identified as having bed bugs, the two adjoining units and the two units immediately across the hallway from the infested unit were also inspected. If no bed bugs were found, the apartments were inspected again 1-3 mo later to confirm the absence of bed bugs. Residents from ≈ 15% of the apartments declined the inspection services, citing their belief that bed bugs were not present.
Across the hall dispersal
The researchers found a way to test their across-the-hall dispersal hypothesis by placing two interceptors baited with a chemical lure outside five infested apartments. The article addresses the question of using lures in these traps thus:
Although chemical lures were used in the interceptors to detect bed bug dispersal, a separate study in nine apartments indicated that the presence of lures did not significantly increase the number of trapped bed bugs (our unpublished data). Thus, we considered the counts from interceptors placed at entry doors or in the hallways to be random catches of bed bugs that were passing through those areas.
In any case, management objected to the traps in the hallways and so they were removed after 7 days. They were then placed behind the front doors of eight infested apartments:
Three of the five pairs of interceptors placed in the hallways trapped two bed bugs per pair after 1 wk, supporting our hypothesis that bed bugs used hallways as a route for dispersal. The mean visual counts from these five apartments before placing the interceptors were 196.4 ± 58.7 per apartment. The average number of bed bugs detected at entry doors over 4 wk period was 6 ± 2 (n = 8 ) and the maximum was 42. Among the 138 bed bugs examined that were caught at entry doors (dispersing), 30% were nymphs, including first instars. Some of the first instars were from eggs laid by trapped adult females as evidenced by the presence of empty eggs in interceptors. The difference between the proportion of nymphs at entry doors versus under furniture indicates that adult bed bugs were 9 times more likely to disperse than nymphs.
It’s not all active dispersal though—who would have thought one could write that after all these years—because standard mechanisms of the spread were observed too, including an infested wheelchair used in common areas, the introduction of infested furniture, “not wrapping infested furniture in plastic before removal from the building” and visits by residents and “guests harboring bed bugs on their clothing or belongings.”
The characteristics of a building-wide infestation
The facts gleaned about this infestation in this building:
- three years after the first suspected introduction, 45% of the building’s apartments were known to be infested, 101 apartments as of April 2009
- in the apartments visually inspected, there were 53 identified infestations; of these, 53% were adjacent apartments on the same floor and 45% were apartments across the hall
- in 40 apartments with a history of reported infestations, only 12 residents were aware of bed bugs; of these 40 apartments, 24 were still infested
- of 40 residents surveyed, 50% received bed bug treatments provided by the building management, 40% tried to control the infestation on their own with chemicals, 35% threw away furniture and 20% used store- or internet-bought pyrethroid-based sprays or foggers. Otherwise, alcohol, bleach and boric acid were used—as well as laundering, covering cracks with tape, placing blankets under doors and using mattress encasements
Information gleaned from interceptor traps in 20 infested apartments:
- while there was a 77% reduction in bed bug counts, after 12 weeks there were still bed bugs in 11 of 20 apartments
- 78% of the trapped bed bugs were nymphs
- 89% of trapped bed bugs were in the outer well of the interceptor “suggesting movement into the trap from the room” and that “most of the bed bugs missed by visual inspections were not on the furniture”
- more than 98% of trapped bed bugs were already dead when counted
This last item is interesting but I’m not sure what to make of it because, in fact, one of the conclusions of this study is that pest control efforts in this building were ineffective at eradicating the bed bugs. This may simply be that elusive line between mitigation and eradication. Unless they’re dying of fright? (Sort of joking but sort of serious—is there any possibility that being trapped makes them, well, not spry let’s say.)
The researchers underscore what to me is an astonishing fact, that 50% of residents in infested apartments were unaware of their own infestations, this despite each tenant receiving a bed bug educational brochure and having the opportunity to attend a seminar.
This is in part what I believe this means: education alone will not solve the problem of bed bugs in our cities. Even assuming a significant investment in educational resources (an insurmountable if at present), there will not be a way to reach everyone.
At some point, you have to have access to all infested locations and then you have to kill all the bed bugs, with something—whatever it is, it must be inexpensive and widely deployable.
What else does this study show us?
This is what the researchers say:
Several of the surveyed apartments in this study were infested for more than two years. The active and passive bed bug dispersal mechanisms observed during this study and the rapid spread of bed bug infestations suggest an urgent need for more effective bed bug monitoring and intervention programs to curb the exploding problem of bed bug infestations. Without such efforts, bed bug infestations will continue to spread in our society and likely become much more widespread in low-income housing in the years to come. Bed bugs cause more than discomfort and pain. Bed bug infestations have economic, social, and legal ramifications (Potter 2006). Thus, it is critical to act early to prevent bed bug infestations from becoming chronic and incurring much greater health and economic consequences.
These are the facts on the ground. From people who know what they’re talking about, not wishful thinkers or would be social engineers.
Clearly, I believe that while many are beginning to recognize the need to act, no one really wants to. It will just take too much money.
But what happens then if we continue on this particular bed bug road?
Active dispersal is an intriguing topic that is near to my heart. Here are some other posts on this subject:
- Where does it say…? 6 essential documents to survive an argument about bed bug dispersal
- Walking bed bugs
- Johnson’s hut, part 1.5
- Across the hall
- Active dispersal, baby
- The wandering females
And here are previous posts about the research of Dr. Wang and colleagues:
- DE vs chlorfenapyr (sorry, an unfortunate title)
- Baited pitfall traps for bed bugs
- Detecting bed bugs using bed bug monitors, Rutgers Cooperative Extension