The active spread of bed bugs in buildings: the stakes for cities

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.

bed bug traps outside apartment door

bed bug interceptors outside apartment door - Wang et al. (2010)

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:

And here are previous posts about the research of Dr. Wang and colleagues:


  1. Sam Bryks

    In view of the findings of this research, I have to rethink my views on “across the hall” dispersal. It would be of interest to know how severely infested the primary units were in these cases… 45% is really a scary figure.
    As there was a period of nearly 3.5 years from the intial infestation, I just wonder about the across the hall relatonship. The visual counts from units at which the interceptors in the hallways showed captures was quite high.. nearly 200 – . The results from equivalent of .7 1.5 man hours of inspection – a lot of work for sure!!, and the effectiveness of the interceptors remains impressive… confirming as noted by others that the best lure is a sleeping body..
    The failure of control by the pc firm is, of course, of great concern. I am sure they were trying hard knowing that the site was under scrutiny.
    This paper certainly shows the importance of the use of interceptors as the best monitor as well as removing many of the insects from the infestation population. A lot more work needed on the dispersal patterns. What degree of infestation results in dispersal through the door.. Do they move laterally more often than across the hall? Is it simply random or are they drawn by people entering their homes (air patterns, CO2? Are they not thermagotrophic (not sure if i got the term – ) like roaches, liking to have the comfort of physical harborage – i.e. cracks and crevice,, perhaps not, as they do travel exposed it seems to find hosts — would be great if someone did a night vision study of their patterns of movement.
    good paper.. scary.. but lots of things to do to get them under control..
    We will get them back to oblivion in due course, but not sure how long it is going to take..

  2. sam bryks

    i got the term incorrect.. It is “thigmatrophic” not thermatrophic.. i first heard it used by Austin Frishman about 30 years ago.. some things do stick in memory..
    it was late after a long day, so forgive me the lapse..

  3. John Burris

    My neighbor and I had a bedbug outbreak last summer. Our lanlord was very attentive and gave us an exterminator. He had to come back two months later for repeat. He says, the bedbugs are 95% gone now. Though I have not had any bites (maybe 2) – I see their ‘glistening shells’ on the carpet. I have wall to wall carpeting! Which I feel makes it doubly hard to get rid of? (Yes)

    I threw all my ‘wood’ furniture out, got new bed frames, covered pillows, bed, etc. Washed all clothing, bedding. But I feel I am just waiting for the next attack.

    It nevers goes away..the dread. the anxiety. Everyone can relate? What is something else, I can do. I even ‘froze’ shoes, pillows, blankets last winter by leaving them on fire escape over night.

    What to do when the next attack begins?


    *I am new on here and have not read anything but this section….

  4. John Burris

    Just wrote above: Perhaps I should say I live in New York (Manhattan).

  5. sam bryks

    As I understand John, Newyorkvsbedbugs was not intended as a site for recommendations, but there are quite a few experts who come here for the excellent resources that Renee has posted, so I’ll try to offer you a few tips..

    1. two months is FAR too long between treatments.. Should have been about 2 weeks .. 3 at the most.. in that two months any eggs that hatched or survivors have gone on to maturity and are now reproducing.. The firm who did the job if they recommended two months between treatments, THEY GOOFED..
    2. Get climbup bed leg protectors .. also called interceptors.. will keep some off the bed and give you and idea of how bad it is..
    3. if you have a vacuum cleaner,, vacuum the bed thoroughly, mattress at seams, box spring at seams and corners,, and vacuum bedframe, sofa, etc..
    at edges of carpets,, and whereever you see them.. behidn pictures, inside drawers, bottom of dresser.. etc..
    4. if you can get a steam cleaner. an inexpensive one and share with your neighbour.. a big help…. not a handheld, but a canister type..
    5. get your unit ready and have a new treatment and then another in two weeks..
    if you don’t have yet, get a box spring encasement for sure, and a mattress encasement too.. use after the first treatment… very important..

    read some of the stuff here and some of the resources.. the National Healthy Homes Centre manual on current methods is very helpful. as is woodgreen’s tenant manual, but not their bed bug resource manual or their long review Bed Bugs are Back…. the tenant manual is good as is the NYC one…
    read those resources…
    hope this helps a bit..

  6. suzanne c curran

    yesterday i came home and was told by another tenant that there where bedbugs in an apt today i asked the property manager and she hesatnly gaveme papers and tttold me there were bed bugs in an apt i asked where no answer she said i was safe and the building would be inspectd next month do these bug get in walls and how can i be sure they arnt carried on shoes i live across from the mail box sincerly suzanne curran at heritage pointe apts staatsburg 12580

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