The bed bug control industry has a spectrum full of techniques for not only exterminating bed bugs, but also detecting bed bugs. Different detection methods can generally be grouped in to three categories:
- passive interceptors and active traps [Pest Solution Services provides this]
- visual inspections by entomologist [Pest Solution Services provides this]
- canine scent detection [Pest Solution Services does NOT provide this]
This new series of articles under the title Detecting Bed Bugs will consist of articles that disect each of the categories above. This third article in the series analyzes bed bug canine inspections.
Canine Inspection
Employing the acute sense of smell of dogs, pest control companies offer canine, K9, or dog scent detection inspections (here on out referred to as “canine inspections”; much less dramatic than “K9” while also not trampling on the industry accepted marketing preference to say “canine” over “dog”) for detecting the presence of a bed bug infestation. This certainly includes a dog handler to be on scene and is probably the most variable detection method we discuss so far. Pest Solution services does not provide canine inspections but due to their presence in the industry it is important we dissect this service for homeowners looking for information.
Physical Manifestation
Canine inspection includes a (possibly certified) dog-handler team. The relationship between handler and dog needs to be strong; they will work as a team and the handler needs to be able to interpret the behaviour of the dog. Likewise the dog must be competent and trained properly. All of this usually includes certification for the handler and dog team, certified by some third party organization which we discuss in the Quality, Costs, and Maintenance section, later below.
After this discussion of physical properties we turn our attention to more abstract properties using personal experience (more than 1000 bed bug inspections) and summarised statistical data and research cited throughout the text.
Detection Success Rate
Like stated before, canine inspections are the most variable detection method, especially when it comes to detection success rates. A 2014 paper reports that the mean detection rate amongst 11 canine teams was 44%.[2] The researchers further summarise: “Four canine detection teams…exhibited significant variance in accuracy of detection between inspection on different days”.[2]
The inaccuracies are also readily admitted by in Advances in the Biology and Management of Modern Bed Bugs as it suggests that all positive canine alerts should be followed up visually or at the very least, “additional monitoring to confirm activity should be considered before any treatment is applied”.[1]
Although one might conclude detection success rate is heavily dependant on handler-dog synergy, this correlation is actually not so easily justifiable. Can’t the dogs sense of smell become extremely impaired due to a overwhelming environmental health and scent conflicts – we have witnessed, first-hand, a rented apartment that the owner could not stand in due to the strong smell of marijuana. Situations like this and hoarding horrors are so frequent that we published in an article, Hoarding Horrors, back in May 2, 2021.
Time Elapsed Until Detection
Mean times vary and depend upon how long the handler is willing to continue searching. Likewise, the research paper we have cited multiple times above, imposed no restrictions on the time that handlers were allowed to take when letting their dog sniff apartments; some teams took longer than others.[2]
It is easy to conclude, however, that canine inspection was designed to be faster than visual inspections; so any structure in which a canine inspection takes longer than a visual detection, is useless. It is important to contemplate what we have discussed so far: canine inspection is a method that is designed to be used in large-scale settings where visual inspections are too laborious. This makes sense when considering the trade-off between accuracy and time/labour to detect.
Classes of Evidence Detected
When detecting a bed bug infestation, you are looking for 6 evidences. The first three would be considered living and the last three are non-living:
- Adult bed bugs
- Any life-cycle stage excluding eggs and adults
- Eggs
- Exoskeleton
- Fecal matter
- Bites
Literature suggests that canine inspection can detect the first 5. Reading a little between the lines also suggests that canines in the industry may only be trained to alert on the first 3 since any alerts on fecal matter and exoskeleton can be considered false positives according to some (especially for follow-up inspections)[1][3]. This means dogs, in general, may be trained to not alert on non-living sources of evidence, namely: fecal matter and exuviae.
Therefore, just as in the case of our discussion on interceptors, we must judge the detection method by its function and design, which leads us to conclude that canine detection, can detect the first 3 classes of evidence and possibly the first 5 classes if trained to do so.
Finally, we note that canine inspection is the poorest in terms of providing evidence to clients (which will serve as a justification for bed bug removal treatment costs, if treatment is needed). Both interceptors and visual inspections, discussed previously, show evidence directly to the client whereas canine inspection is a bit more cryptic in that the client isn’t shown the evidence and the conversation remains between dog and handler unless the handler opts to visually inspect positive alerts by the dog and find the evidence.
Reliability (False Negatives/Positives)
False positives are the biggest challenge canine inspection admittedly faces. After reporting a false positive mean average of 15% false positives with a max of 57% for one team (data used from three separate experiments – each varying in method), researchers stated: “The false positive rate was positively correlated with the detection rate”[2], suggesting that teams which alert correctly the most, also have the most false alerts.
As for false negatives, then it is possible just as with other detection methods, especially if there is some environmental condition or strong smells that prevent the dog from carrying out its task properly. What is more likely is that companies simply refuse to perform canine inspection in such conditions.
Quality, Costs, and Maintenance
Although costs are hard to predict since Pest Solution Services does not have direct insight and experience in pricing and charging for canine inspections, a general idea can be taken from the fact that a company would incur expenses from two perspectives: the first being dog training, maintenance, and transportaion for each job, and the second being handler labour.
Quality for canine inspections is something monitored and acknowledged in the industry as there are multiple third party sources that give certification to dog-handler teams. This is a form of quality control; anyone who needs assurance they are getting something worthwhile can ask about certification. For example, one organization that provides certification is the World Detector Dog Organization which has actually certified seven (at the time of writing) bed bug detection dog and handler teams in Ontario.[4]
As for maintenance, then the homeowner may need to make things dog-friendly and try their best to have an environment where nothing interferes with the dog’s scent detection.
Conclusions
Canine inspections for detecting bed bug infestations are quite unnecessary. No direct communication between homeowner and detection tool, inconsistent success rates, chances of false positives are higher than both interceptors and visual inspections, environmental anomalies can reduce reliability, and client is never shown evidence (unless visual inspection is performed). If this seems harsh, we welcome any research that conflicts these findings with a condition that the studies are done in field environments.
To conclude all of the above information, we can condense it in to pros and cons. The list below lists the pros and cons of bed bug canine inspections as a detection method, with each point taken from its respective place in the above discussion. Citations in this summarised list are omitted and should be found in the above paragraphs, if needed.
- PRO: Can detect 3 or 5 classes of evidence.
- PRO: Certification is available dog-handler teams so clients can verify quality.
- PRO: Instantaneous inspection results.
- CON: Dog may not be able to cope with various environmental obstacles.
- CON: Extremely unstable detection success rates – lowest among all three detection methods.
- CON: Highest rate of false positives among all three detection methods
References
- [1] S. L. Doggett, D. M. Miller, C.-Y. Lee, and D. Miller, Advances in the Biology and Management of Modern Bed Bugs. Newark: John Wiley & Sons, Incorporated, 2018, pp. 244.
- [2] R. Cooper, C. Wang, and N. Singh, “Accuracy of Trained Canines for Detecting Bed Bugs (Hemiptera: Cimicidae),” Journal of economic entomology, vol. 107, no. 6, no. 6, pp2171-2181, 2014, doi: 10.1603/EC14195.
- [3] M. Pfiester, P. G. Koehler, and R. M. Pereira, “Ability of Bed Bug-Detecting Canines to Locate Live Bed Bugs and Viable Bed Bug Eggs,” Journal of economic entomology, vol. 101, no. 4, pp.1389-1396, 2008, doi: 10.1603/0022-0493(2008)101[1389:AOBBCT]2.0.CO;2.
- [4] “Certified teams,” W.D.D.O, 21-Feb-2014. [Online]. Available: https://www.wddo.org/certified-teams/. [Accessed: 04-Apr-2022].
- [5] S. L. Doggett, D. M. Miller, C.-Y. Lee, and D. Miller, Advances in the Biology and Management of Modern Bed Bugs. Newark: John Wiley & Sons, Incorporated, 2018, pp. 250.
