While there is plenty of literature on bed bug biology, management and ecology in traditional settings, such as residential homes (Wu et al. 2014), multi-family dwellings (Cooper et al. 2016) and hotels (Penn et al. 2017), the understanding of how bed bugs establish and infest non-traditional settings is lacking. By “traditional,” we mean locations where there is an ample food source during the times that bed bugs are active; in other words, these are locations where people sleep overnight. Settings where there are no overnight accommodations are not conducive for bed bug infestations. Yet we do see these in the field.
The Rutgers Entomology lab had a unique opportunity to conduct a case study in a non-traditional setting, a cubicle-based office space. We received a call from an office complex where the office had a two-year history of multiple confirmed sightings of bed bugs. All employees vacate the premises at 6 p.m. and do not return until at least 6 a.m. So we took this opportunity to monitor the space in order to understand what was occurring. Some of the findings were a bit surprising!
“NON-TRADITIONAL” SETTINGS.Those in the pest control industry know all too well that bed bug sightings are not uncommon in settings that are often not thought of as being associated with this important urban pest. We have found bed bugs in movie theaters, offices, retail centers, emergency rooms and many other places that people don’t stay overnight. It is generally thought that these are often isolated introductions. While that may be true in general terms, do we really know?
Bed bugs require a blood meal between each molt as they mature. They feed every couple of days during nighttime hours, typically between 1-5 a.m. (Doggett et al. 2012). With this understanding, we typically do not think of bed bugs as being able to easily establish a breeding infestation in environments that do not have readily available food sources during overnight hours.
So when we received the call about a two-year history of repeated sightings in the same area, we became quite interested. What was going on? Were there repeat introductions over two years? Was there a problem at an employee’s home that has not been solved? Was there an established population in the office? These questions all led us to conduct a case study at the location.
THE STUDY. In mid-December 2017, we installed 270 bed bug interceptors (10-cm diameter ClimbUp HD) in 58 cubicles and pod-seating areas that the employees used. In each cubicle, one of the interceptors had a lure (SenSci Activ lure) installed in the inner well. The area was approximately 9,400 square feet. We then returned six times over a three-month period to inspect all the interceptors and recorded all captures by date and precise location. Spatial analysis was conducted on the captures to determine the distribution and movement patterns of bed bugs throughout the study.
Based upon findings, we conducted two treatments in the evenings using only amorphous silica dust (CimeXa) in small areas including the cubicles that had bed bug captures. The treatments were conducted approximately one month and two months after installing the interceptors. Immediately following each application of the dust, we left a dry ice trap in each location to lure roaming bed bugs to the treatment area from the nearby vicinity.
BREEDING ACTIVITY. Upon our first inspection of interceptors, we noted that the activity was concentrated heavily around a small set of cubicles. A total of 11 bed bugs were captured, with 7 of those found in two adjacent cubicles. The remaining four captures occurred in dispersed locations elsewhere. We placed dry ice traps overnight in the cubicles where we had captures to see if there were more bed bugs. Upon returning in the morning, we did indeed find two more in the cubicles that had the concentration of bed bugs. We therefore conducted a visual inspection of all materials in the cubicles and found an active breeding harborage (see Fig. 1 at left) in a chair in one of the cubicles, which was properly disposed of upon the finding.
TARGETED TREATMENTS.During the second inspection, we again captured bed bugs. The pattern of captures was similar. Out of a total of 18 bed bugs captured, the majority (10) were found in the same two cubicles as where they were concentrated during the first inspection. The remaining eight were found singularly, spread out in other cubicles or pod seating areas. We treated the cubicles and pod seating areas that had bed bug captures using only amorphous silica dust and installed a dry ice traps overnight. We applied 73.5 grams in an area about 310 square feet, including cubicle wall voids and other spaces in the floor space. This time, we did not capture any bed bugs in the dry ice traps.
A total of three bed bugs were captured during the following two inspections. We again treated in the areas where the three additional bed bugs were captured following the fourth inspection using the same process. We applied only 39 grams in an area about 270 square feet. No bed bugs were captured during the final two inspections (see Figure 2).
SUMMARY.The first important finding from this case study is that bed bugs are capable of establishing breeding infestations in environments that do not have people sleeping overnight. While the chances are that sightings in such non-traditional settings are introductions, we cannot discount the chance that there is an active infestation.
The spatial analysis showed that the majority of bed bugs stayed aggregated or clumped in an area within close proximity to where the breeding site was found (see Figure 3). Yet, the total size of this infestation was small with only 32 bed bugs captured over a three-month period. Therefore, monitoring is essential to eliminating bed bug infestations in non-traditional settings such as office spaces. Monitoring is necessary in identifying any possible breeding harborages. Once identified, removing the harborages and conducting targeted treatments using a limited amount of insecticides can achieve elimination of bed bug infestations.
Prior to December 2017, the office space had 37 confirmed sightings of bed bugs over a period of two years (2016-17). A year following our case study, no further sightings have been reported in the office spaces, further confirming that elimination was indeed achieved. Shannon Sked and Changlu Wang are with Rutgers, the State University of New Jersey, Department of Entomology. Michael Levy and Kathryn Hacker are with the University of Pennsylvania, Department of Biostatistics and Epidemiology.
Cooper, R., C. Wang and N. Singh. 2016. Evaluation of a model community-wide bed bug management program in affordable housing. Pest Manag. Sci. 72: 45–56. Dogget, S.L., D.E. Dweyer, P.F. Penas and R.C. Russell. 2012. Bed bugs: Clinical relevance and control options. Clin. Microbiol. Rev. 25: 164-192.
Penn, J.M., H.J. Penn, M.F. Potter MF and W. Yu. 2017. Bed bugs and hotels: Traveler insights and implications for the industry. American Entomologist 63: 79-88.
Wu, Y., D.M. Tracey, A.M. Barbarin, C.M. Barbu and M.Z. Levy. 2014. A door-to-door survey of bed bug (Cimex lectularius) infestations in row homes in Philadelphia, Pa. Am. J. Trop Med Hyg 91: 206-210.