Bed Bugs 101 - Pesticide Impregnated Mattress Covers

• The covers are not likely to be repellent enough to prevent hungry bed bugs from feeding on the person sleeping in a bed that has one of these covers on it.
• The covers are not likely to control bed bugs by killing them as they come in contact with the treated fabric. Bed bugs typically require exposure to pesticide residues for many hours or days before morality occurs. Bugs are not likely to spend very much time in contact with the cover.
• The concepts of repelling bugs and killing bugs are contradictory. The reality is that the covers probably do a little of both, but not a lot of either.
• The covers don’t prevent bed bugs from infesting and living inside the box spring under the mattress and in the bed frame.
• It is unnecessary to introduce a chemical into the sleeping environment when non chemical options exist (encasements) that have been proven to be effective and are recommended almost universally by bed bug experts around the world.

Within the past year or two, pesticide impregnated mattress covers have become commercially available to consumers as another tool to combat bed bugs.  In general, we have some very serious concerns about the use of chemically impregnated mattress covers and the claims that are made by manufacturers about these products.
 

The basis for our position is more thoroughly explained in the information below.

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
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 the most effective and appropriate method 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?
Bed bugs are very different than mosquitoes, so one cannot simply assume that because chemically impregnated fabrics work well for mosquitoes that they will also be effective for bed bugs.  To understand this it is important to consider what impregnated covers are intended to do, then consider if it is likely to be effective with bed bugs or not and why?

Repelling Bed Bugs:

The idea of repellency is that when the bug encounters the impregnated cover it will be repelled by the presence of the pesticide. However it is important to realize that a "force field"  is not generated by the application or inclusion of chemicals into the fabric.  A chemical repellant is designed to achieve a threshold of discomfort to which certain insects are averse to coming into contact with.For example use of DEET as a mosquito repellent will reduce the number of mosquito bites that a person wearing the repellent experiences, still mosquitoes that are hungry enough will still land on the person and bite them. Mosquito nets work well because mosquitoes can fly long distances to find people to bite and feed on and will often fly from home to home to find someone to feed on, or may just find a wild animal or pet to feed on.

Bed bugs are very different from mosquitoes.  They infest a home and are dependent upon the people living in that home for a blood meal.  They don’t have wings and can’t simply fly away or even crawl away to find food somewhere else.  For this reason it is very unlikely that any impregnated cover would be so repellent that it would prevent a bed bug from acquiring its blood meal.  Research conducted on at the University of Kentucky on the repellency of pesticides, like Permethrin, demonstrated that repellency of these chemicals is limited.  The presence of bed bug odors such as those found in infested areas (feces, other bugs etc.) was enough to cancel out the repellent effects of the insecticide.  Furthermore, the impregnated covers are going to be covered by bed linens further reducing the likelihood of a repellent effect.

Killing Bed Bugs

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 (refer to the following publications for more information on bed bug resistance to pesticides hyperlink to several publications) In order for bugs to be killed, they would need to spend a far greater amount of time in contact with the treated cover then they are likely to.  So why won’t they be in contact long enough?

• 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 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 not long enough to acquire a lethal dose of pesticide in most cases.
• Realizing that extended 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.

Concepts of Repellency and Contact Mortality are Contradictory!

On one hand impreganated mattress covers are intended to repel, on the other hand they claim to kill through exposure of bugs to the treated fabric.  These two concepts are, in fact, contradictory.  If they are an effective repellent then bugs should avoid coming near them and would thus not be killed.  So which is it, do they work by repelling bugs or by killing bugs?  The reality is they probably do a little of both but not a lot of either, for the reasons covered in the sections above.

The Bed Bug 101 Position on Chemically Impregnated Covers

When it comes to chemically impregnated covers, we are concerned about what we believe are bold and misleading claims associated with impregnated mattress covers and the role they play in a pro active or reactive bed bug program. As always caution should be taken when relying on any method that claims to have 100% effectiveness and/or provide long-term safeguards against infestation.  To date, there is no product that is 100%  effective in controlling bed bugs and nothing that will prevent bed bugs from being introduced.