Early Detection Tools & Methods

The ability to detect bed bugs during the early stages of an infestation when only a few bugs are present is absolutely critical, however until recently early detection tools and methods have been severely limited. Mattress and box spring encasements were the first early detection tool available. Now we are seeing a number of detection tools and methods including canine scent detection, CO2 monitors and passive interception devices that are making the early detection of bed bugs a reality. It is important to note that while monitoring tools and methods have certainly improved; no tool or method exists that is completely reliable in detecting bed bugs. For this reason, regardless of what method or device implemented, the failure to identify bugs cannot be used as an indicator that no bugs are present and it always recommended that a combination of methods be used to improve the likelihood of finding low activity.

The following is an overview of the current monitoring methods and tools:

Visual Inspections:

Visual inspections are time consuming, labor intensive and perhaps the least reliable of all inspection methods when it comes to detecting low level infestations where only a few bugs are present. The reason that visual inspections are so unreliable is based on the secretive and cryptic nature of bed bugs and their propensity to hide in very narrow cracks too thin to see into or areas that are not visually readily accessible such as inside sofas, under baseboards, or beneath floor boards. Despite these limitations, visual inspection is still the most common method, as it can be performed by anyone that knows what to look for and does not require the purchase of specialized devices. All that is needed is a good flashlight and perhaps a magnifying lens to aid in seeing eggs and small nymphs. (See sections on Biology and Behavior and Early Detection)

Mattress Encasements:

Encasements for mattresses and box springs were the first early detection method available. In addition to protecting mattresses and box springs from becoming infested, encasements have helped to expose many bed bug infestations by removing the many hiding places that exist on mattresses and box springs and forcing bed bugs out into the open on the smooth exterior of the encasement where they can be readily seen and dealt with. There are many brands of encasements and they are not all created equally, nor are they all effective for use as a bed bug detection and/or management tool. For detailed information on encasements see the section on Mattress and Box Spring Encasements.

Canine Scent Detection:

Canine scent detection has become an increasingly popular inspection method for the detection of low level infestations. The biggest problem is that there are great disparities in the quality and effectiveness in the canine scent detection services that are available in a given area. A well run canine scent program can yield highly effective results and will often reveal infestations that would have been missed during a visual inspection. Unfortunately, the prevalence of poorly run programs is a real threat that may result in the discrediting of this valuable inspection method. There are two major concerns that are associated with canine scent inspection programs. The first is the concern that dogs may fail to detect bed bugs that are present and the second is the converse, where dogs falsely indicate the presence of bed bugs. Most canine scent detection firms adverstise accuracy rates of 95% or greater. This high level of accuracy has been demonstrated under controlled conditions in a University of Florida study. However, much lower accuracy rates were observed in a study conducted by Rutgers University under real world conditions using naturally infested apartments.  IWhile it is difficult to deal with the dogs failiure to detect infestations, the issue of false alerts can be addressed by requiring some type of verification system be in place to confirm the presence of bed bugs following a positive indication by the dog. One method is to produce the evidence of the infestation (see section on How do I know if I have bed bugs, or early detection for more information on verifying the presence of bed bugs), the other is to institute a double blind verification system (see section on Canine Scent Detection for a complete discussion of this topic)

Bed bug sniffing dog inspecting sofa

Passive Interception Devices:

Passive interception devices arevery simple, inexpensive pitfall style traps thatcan be placed under the legs of bed frames and upholstered furniture. Once installed, they intercept and capture bed bugs as they travel to the sleeping and resting areas. The interception device can also capture bed bugs as they migrate away from beds and furniture, preventing them from infesting other parts of the structure and from getting into personal belongings that are difficult to treat.

The concept behind how interception devices work is that it allows bed bugs to climb the exterior of the device which is textured but then fall into a well that has smooth slippery sides that they are unable to climb and thus become trapped inside the well. Once the interceptors are placed under the legs of the furniture they work 24/7 with very little maintenance required other than occasionally emptying trapped bugs and periodically cleaning the wells or cleaning and relubricating the walls of the well with cotton ball dipped in talcum powder (depending on which device you are using).

The term passive monitor is used to describe these types of traps because there are no lures or attractants used such as CO2, heat or other attractants to entice the bed bugs into the device. In reality however, interception devices are anything but passive. By placing them under the legs of the bed, the person sleeping in the bed serves as the attractant, and there is no better lure than the bugs food source. In fact field research demonstrated that interceptors, left under the legs of beds for one week, were more effective in detecting low level infestations than active CO2 monitoring devices.

It is important to pull the bed away from the wall and not to allow linens, comforters, dust ruffles or other items to hang off the bed in contact with the floor, so the bugs have no alternate path onto the bed, forcing them into the interceptors.

Blackout Bed Bug Detector under bed leg

ClimbUp Insect Interceptor with bugs trapped outer and inner wells. Bugs in outer wells trapped in route to bed, bugs in inner well trapped when leaving bed.

ClimbUp Insect Interceptor on Sofa

University research has demonstrated that passive intecrpetion devices are among the most effective tools available for the detection of bed bugs and also play a role in reducing the number of bed bugs during the management effort, and are thus also a bed bug management tool. The use of interception devices can also be extended to areas away from sleeping and resting areas as bed bugs tend to travel throughout infested dwellings and are proving to be much more mobile than previously believed.  For this reason, interception devices placed in the corners of rooms and in closets can also help aid in detection of low level infestations, evaluation of the bed bug management effort as well as providing insight into areas where bed bug activity exists.

Commercially Manufactured Active Monitoring Devices:

Monitoring devices that employ the use of carbon dioxide have been developed for the detection of bed bugs. In addition to using CO2 as the primary attractant, some of these devices also employ other attractants such as heat and chemical lures. At the current time only one commercially manufactured CO2 traps is available, the Verifi Bed Bug Detector by FMC.  In addition to Verifi, the NightWatch® Bed Bug Trap (manufactured by Biosensory) may become available again in the future but issues with the registration of this device have caused it to be pulled off of the market.  Both are similar in concept, using CO2, heat and a chemical lure to attract bed bugs, but there are also some significant differences.


NightWatch Bed Bug Monitor


Verifi Bed Bug Detector

The effectiveness of the Verifi detector is still being evaluated but research has indicated that it has the ability to activate bed bugs within 5 feet of where the device is set.  Therefore, while the best possible protocol to use this monitor is still being evaluated, an imaginary 5 foot radius around where the monitors are set should be used to assist in determining the coverage area of a monitoring program.  In addition, preliminary field testing has shown that the Verifi has the ability to detect a high percentage of low level infestations and will most likely be an important detector in bed bug monitoring programs moving forward.

As mentioned for passive monitors, active monitors can also be used in areas away from sleeping and resting areas to monitor the activity of bed bugs but due to the cost of active monitors this is not as economically practical as with passive interceptors that typically cost much less per device.

Do It Yourself (DIY) Monitor:

A simple but very effective monitoring device can be constructed using a pet food bowl, masking tape, an insulated container and dry ice. The trap design comes from research conducted by Rutgers University entomologist, Dr. Changlu Wang. This trap design is very effective and was shown to capture bed bugs in low level infestations in a field study conducted in an apartment setting.

While simple in concept, if the proper pet food bowl is not utilized the trap will not be effective. Additionally there are potential hazards associated with the handling of dry ice that must be considered. These hazards include but are not limited to asphyxiation if too much dry ice is used for the volume of the area being monitored and burns that can easily result if dry ice comes in contact with the skin. People using this monitoring technique must familiarize themselves with the safe handling of dry ice and exercise proper care when operating the monitor. Due to these concerns we recommend that pest management professionals do not use home made monitoring devices at client locations but rather purchase the commercially available devices that have been manufactured for monitoring/detecting bed bugs. Additionally, we want to be certain that anyone that chooses to use this method recognizes that this is simply a monitoring and detection device, and is not a control tool nor is it a solution for bed bugs.

Click Here to watch the Bed Bug TV Episode on the DIY Bed Bug Monitor.

Dry ice trap using pet food bowl
and insulated cooler containing dry ice


As stated previously, it is important to note that while monitoring tools and methods have certainly improved; no tool or method exists that is completely reliable in detecting bed bugs. For this reason, regardless of what method or device implemented, the failure to identify bugs cannot be used as an indicator that no bugs are present. Low level infestations can still escape detection regardless of the detection methods implemented. In addition, detection tools are not to be confused as a solution for bed bug problems, their primary function is for the detection of bed bugs.

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