First, the study.
Naylor, R. A., and C. J. Boase. 2010. Practical Solutions for Treating Laundry Infested With Cimex lectularius (Hemiptera: Cimicidae). Journal of Economic Entomology 103 (February): 136-139. doi:10.1603/EC09288.
In keeping with our recent interest in the first line of these research abstracts, here is this one:
The common bed bug, Cimex lectularius (L.) (Hemiptera: Cimicidae) is known to become associated, from time to time, with clothing or linen.
From time to time…
The author surveyed 100 websites offering information on bed bug control in 2007, and found specific, practical information lacking.
Washing
3.2 kg dry weight of laundry, about 7 pounds, washed at 30°C/86°F, 40°C/104°F and 60°C/140°F in a 90-minute cycle wash (that’s the standard cycle in the UK) with a standard laundry detergent. Bed bugs (10 adults, 10 third instar nymphs, 10 eggs) were placed inside clothes pockets, in cotton pouches and sealed with a sandwich bag clip.
The 40°C/104°F cycle killed all adults and nymphs, but 75.6% of the eggs survived.
The 60°C/140°F cycle killed all stages.
Tumble drying
7 pounds of laundry (dry) in dryers set to “hot” and “cool” for 10 minutes and 30 minutes.
The temperature in the “cool” cycle never got above 30°C/86°F.
The 10-minute “hot” cycle did not kill all bed bugs, probably because it took more than 15 minutes to get above 40°C/104°F. (The authors reference the published thermal death point from previous work in the 1930s-40s in the range of 40-45°C/104-113°F.)
30 minutes in the “hot” cycle killed all life stages.
Here is a graph of the temperature logged during these drying cycles. The 40-45°C zone is the (previously published) dead zone, but it took more than 15 minutes.
temperature change over time, hot (A) and cool (B) drying cycles - Naylor & Boase 2010
Cold soaking
7 pounds of laundry in about 15°C/59°F tap water, without detergent.
Almost nothing dies if soaked for two hours. But, interestingly, all adults and nymphs died when soaked for 24 hours.
The eggs, however, survived. All of them.
Dry-cleaning
Professional dry cleaning with perchloroethylene.
100% kill of bed bugs and eggs.
Freezing
A laundry bag of 2.5 kg (about 5 and a half pounds) in a freezer drawer of a standard household freezer with a minimum temperature of -18°C/-0.4°F — a separate test was done with bed bugs placed in pouches in the freezer for two hours at -17°C/1.4°F.
2 hours at -17°C/1.4°F killed all bed bugs and eggs when placed directly (not in clothes) in the freezer. But when a bag of laundry was placed in the freezer, it took about 8 hours for the temperature at the center of the bag to reach -17°C.
The researchers advise caution about the regional differences in laundry equipment:
[T]here are regional differences in the operation and performance of domestic appliances that stress the importance of understanding the local situation when making recommendations. For example, washing machines in Europe typically heat their water to the user-selected temperature, whereas washing machines in the U.S. and Australia tend to use the household hot water supply and are therefore limited by the temperature of the water coming from the boiler. Furthermore, wash cycles in the U.K. typically last 90-120 min, whereas in the U.S., wash cycles of 20-30 min are much more common (Procter 2000). As Tables 1 and 2 demonstrate, differences in temperature and duration may make the difference between success and failure in terms of clothing disinfestation. These differences emphasize the need for caution when considering adopting advice generated in one country, for use in another.
For comparison of these results with some American laundering tests reported by Potter et al. in 2007, see this PCT article.
Q&A
Richard Naylor is a doctoral student at the University of Sheffield (UK). Take a look at his bed bug photographs here. I particularly like this one:
Bedbug. Copyright Richard Naylor.
He generously answered our questions via email.
New York vs Bed Bugs: Your group regularly produces some of the most fantastically interesting research about bed bugs and yet I have to say it is a joy to ask you about something as simple as laundry. Because in fact it is not so simple… so it is wonderful that you took an interest in this subject. I like that your study shows that people have options (e.g., you can disinfest clothing even if you don’t have access to a dryer), but you note that regional differences in laundry equipment are important to consider. So, with that in mind, if we were to make judgments based on temperature and time (in places where one doesn’t really know the temperature of washers and dryers but can use, say, a household thermometer for some limited testing), what would be a useful rule of thumb? Often people are confused by thermal death points, especially because they seem not to be stable in the literature and have much to do with method and duration of exposure.
Richard Naylor: The important thing does seem to be the temperature, whether washing or drying. 40 degrees [Celsius] seems to be the magic number. In simple terms this is about the temperature of a nice warm bath, so it doesn’t need to be scolding hot. Some washing machines don’t heat their own water and so the maximum temperature they can achieve is the temperature that the boiler is set to. If your hot tap produces water that is slightly too hot to hold your hands under for any length of time, it is probably fine for killing bedbugs. Unfortunately one can’t get round having to know something about their washing machine if they plan to use it for treating bugs. Perhaps it would be simpler to fill the bath with hot water. As long as it is a bit too hot to hold your hands in it should be fine. Hot water penetrates the fabric much quicker than hot air, so time isn’t really a factor as long as all the air is pummeled out of it.
New York vs Bed Bugs: Did you really read 100 bed bug fact sheets on the internet? I am honestly impressed by that diligence because that sounds like torture to me. Did you find great variability in the practical information on offer?
Richard Naylor: Yes I did. A lot of the sites offering advice were run by local councils. The advice wasn’t particularly variable because people just republish the same “knowledge” over and over again. I just kept a tally of every mention of “hot wash”, “tumble-dry” etc. and worked my way down a google search. Every now and then you stumble over a blinder, involving a bloody steak and a roll of sellotape, which keeps the motivation up! I keep a folder on my computer of all the best bedbug misinformation I can find on the web!
New York vs Bed Bugs: Can I ask you what you are working on? What are some of the interesting questions in need of answering?
Richard Naylor: I am currently interested in their ecology and dispersal. We actually know a lot more about the ecology of swallow bugs than we do of bedbugs, simply because when an infestation is discovered, it is normally treated straight away. People don’t want to wait a few weeks for studies to be made and experiments carried out. The solution I have come up with is to build about a dozen 3 meter long arenas complete with blood feeding station and around 200 bedbugs in each. I am trying to understand how they behave in an infestation and to figure out what factors are important in driving their dispersal.
New York vs Bed Bugs: I once saw what looked like a carved wood panel of mating bed bugs at your university’s website (can’t seem to find it again)—I am curious about just how old that is? Is it an artifact of the current interest in bed bugs or is it from much earlier? It is beautiful and I wonder if you’ve always had it.
Richard Naylor: Well spotted. We (though not me) started studying bedbugs at Sheffield University about 15 years ago. Mike [Siva-Jothy] used to be particularly interested in sexual conflict, which is the idea that males and females of a species are purely out to do the best for themselves as they can, often at the expense of the opposite sex. Bedbugs are a prime example, as males will mate with females much more often than the females require to stay fertile and as a result the females live about 25% less long than they would otherwise. We believe that traumatic insemination arose out of sexual conflict as a way of males preventing females from exerting choice over paternity.
Anyway, the carving was commissioned about 6-7 years ago and is made up of lots of images from old books and photographs around the department. The bedbugs are copied from an electron micrograph that we had done of some of our bugs at the time.
These pages may be of related interest:
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would you recommend heat/steam or freezing treatment for bed bug elimination. i live in a 2 bedroom apartment in a 3 family house, and it seems as if my apartment is the only one affected right now, especially my bedroom. i’d like to get professional treatment, but don’t know which is better.
Hi Heather, a professional can use a dry vapor steamer to treat your home in conjunction with other methods and materials, such as pesticides and desiccant dusts, vacuuming and disinfesting clothes and belongings as appropiate. You can also learn to use a dry vapor steamer yourself if you had access to one. Using steam alone without other methods may also work but it depends on the characteristics of your infestation and the skill and persistence of the person applying it. If your infestation is not advanced, conventional treatment by a professional with steam plus other materials is a good option.
Heat is a serious process where they come in with specialized equipment and elevate the temperature in your home over several hours. If money is no object, and provided you contract a good company that has experience, then heat is a very good option and I would recommend it as it can be effective in a single treatment, though of course failure does occur sometimes. Make sure they are experienced, however, in order to reduce the risks that they could make a mistake and cause damage to your home or property.
If by freezing you mean the C02 treatment known as cryonite, then the thing to understand is that, like other thermal options, it has no residual action. The C02 “snow” must contact the bed bugs directly in order to kill them. The likelihood of this direct contact happening in a single treatment I think is not high except in very small infestations. You may require, as with other methods, multiple treatments and the use of other materials as well. You have to consider the costs of these options and still of course the professional must be skilled and know bed bugs; that is more important than anything else, no matter what method you opt for.
Easier said than done but I’m sorry that I can’t recommend anyone. Best wishes…
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