Within the past year or two, pesticide impregnated mattress covers have become commercially available to consumers as another tool to combat bed bugs
Difference between Mattress Encasements & Chemically Impregnated Covers
Chemically impregnated covers are often confused with mattress encasements. It is important to realize that the chemically impregnated covers are radically different than bed bug encasements both in concept and function. For this reason it is important to understand the differences between encasements and chemically impregnated covers as well as the concerns that we have regarding efficacy claims.
Encasements that have been designed for bed bugs are used to completely envelop (encase) the mattress as well as the box spring. A properly designed encasement will be entry proof, escape proof and bite proof. They serve to provide a number of benefits including 1) prevent bugs from getting into mattresses and box springs; 2) aid in early detection of bed bugs; 3) salvage infested mattresses and box springs; 4) increase the efficiency and effectiveness of eradication of bed bug infestations. (See Section - Mattress and Box Spring Encasements)
Currently encasements are recommended by virtually all bed bug experts as one of the most effective and appropriate methods for addressing mattresses and box springs.
Chemically Impregnated Mattress Covers
Most, if not all, of the chemically impregnated mattress covers do not envelop the mattress or box spring as encasements do. Instead they are similar to a fitted sheet and only cover the top and sides of the mattress. Most, if not all, chemically impregnated covers are impregnated with insecticides, most commonly Permethrin. The covers are intended to either repel or kill bed bugs that come in contact with them. Manufactures also make claims for long term effectiveness of these covers.
Not a New Concept
The use of pesticide impregnated fabrics for beds is not a new concept. Permethrin impregnated bed nets are widely used to help combat mosquitoes that transmit malaria. Mosquito nets are hung like a tent around the person sleeping in the bed. The netting helps prevent the mosquitoes from easily accessing the person while they sleep and either repel the mosquito, causing it to seek a blood meal elsewhere or kills the mosquitoes that land and stay on the treated net long enough to get a lethal exposure.
With the current resurgence of bed bugs it didn’t take long for the concept to be applied to bed bugs in the form of insecticide impregnated mattress covers. Most of the covers are impregnated with Permethrin, however there are also some that are impregnated with non-toxic oils.
Do Chemically Impregnated Covers Work?
Chemically impregnated covers are usually impregnated with the synthetic pyrethroid Permethrin. University studies have clearly demonstrated high levels of pesticide tolerance and resistance to this class of pesticides:
A recent study out of Ohio State University demonstrated that a permethrin impregnated fabric was not repellent to bed bugs and resulted in rather quick mortality of bed bugs exposed to the chemically impregnated fabric (for the complete article click on the following link http://www.mdpi.com/2075-4450/4/2/230 ). This research clearly demonstrates that impregnated covers can kill even resistant bed bugs if they spend enough time in contact with the treated fabric. While the study strongly suggests that permethrin impregnated liners can be used to kill bed bugs in infested homes, consumers should be aware that in a typical infestation many bugs are likely to exist in areas where they are not exposed to the treated liners and thus liners should not be considered as stand-alone solution to a bed bug infestation.
When considering the use of liners it is important to take the following points into account.
- While some bed bugs can be found living on the mattress, most do not live on the upper surface or sides of either mattresses or box springs. Instead they live inside box springs in bed frames, and in the furniture throughout the infested dwelling.
- Bed bugs living away from the mattress will climb onto the mattress merely to gain access to the sleeping person for a blood meal. They feed and then scurry back to wherever they came from. The amount of time that they spend on the actual mattress is very limited and may not be long enough to acquire a lethal dose of pesticide in most cases.
- Realizing that contact is needed to kill a bed bug a second problem occurs when you add in bed linens. The mattress is less likely to provide a contact exposure simply because people traditionally place a fitted sheet over top of the impregnated cover. This creates a barrier between the bed bug and the pesticide, reducing or eliminating the contact exposure needed to begin killing bed bugs. It would be unwise to eliminate the fitted sheet as this would place the sleeping person in constant contact with the chemically impregnated cover and raises concerns over chronic exposure to pesticides.
The Bed Bug 101 Position on Chemically Impregnated Covers versus Encasements
Chemically impregnated mattress liners vs. mattress and box spring encasements are based on two entirely different philosophies and each takes a different approach to bed bug management. Neither one should be considered as a stand-alone method for control of a bed bug infestation, but instead are just one of a number of control measures required for the effective elimination of bed bugs.
Impregnated covers are designed to kill bed bugs that come in contact with the treated material for a sufficient amount of time. Encasements, on the other hand, are designed to eliminate hiding places associated with the mattress and the box spring. With the hiding places eliminated, other control measures can be implemented in a much more effective and efficient manner.
Ultimately, our position has always been to address the bed bugs associated with beds with non-chemical methods. For this reason we favor encasements over chemically impregnated liners. We also believe there is greater benefit in trapping bed bugs within encasements and more importantly removing future hiding places for bed bugs than relying on mortality of bed bugs exposed to treated liners.