Editor’s Note: The following article appeared on Mike Merchant’s blog, “Insects in the City,” which can be found at http://insectsinthecity.blogspot.com. The blog offers readers news and commentary about the urban pest management industry and is excerpted here with permission of the author.
The nice thing about an emergency pest problem, like the current bed bug epidemic, is that such problems attract a lot of attention from the research community. Here I’d like to present some research from two British scientists from the University of Sheffield, R.A. Naylor and C.J. Boase, about how to kill bed bugs in bedding and clothing using laundering procedures.
Knowing how to “disinfest” clothing is important to pest control, because, as the authors so carefully explain, bed bugs “may seek harborage among clothing stored close to the bed, or may be entangled with bed linen while it is being changed.” And, “once associated with clothing or linen, there is a risk that bed bugs may then escape insecticide treatments, and may be transported to new locations.”
Although there have been many recommendations on the Internet and in print concerning how to disinfest laundry, Naylor and Boase point out that such recommendations are often vague or conflicting and have been based on little formal research. So they set out to look at the temperatures and conditions necessary to ensure 100 percent mortality of adult, nymph and egg stages of bed bugs.
To do this they took laboratory-reared bed bugs and sealed them in cotton bags. These bags were then placed among sheets or in the pockets of clothing to assess mortality of standard cleaning methods. The results were enlightening and should help in recommendations for how your customers can ensure maximum effectiveness of methods to disinfest household articles.
A summary of the results of this study follows:
- Freezing can kill bed bugs. Reducing temperatures to -17°C (0°F) for two hours will kill all bed bug life stages (about the temperature of a chest freezer, not a refrigerator freezer). A 5½-pound batch of clothes, however, does not drop to 0°F immediately. The researchers found that it took about eight hours for the temperature in the center of that wad of clothes to reach killing temperature. Thus, PMPs should put clothes in the freezer for at least 10-12 hours.
- Bed bugs also are susceptible to high temperatures of 40-50°C (104-122°F). In order to reach these temperatures, clothing to be disinfested can be placed in a large tumble drier at the HOT setting for at least 30 minutes (for a 7.7-pound load). A 10-minute HOT tumble dry only killed about 75 percent of nymphal bed bugs and 85 percent of adults. Interestingly, the COOL cycle killed almost no bed bugs.
- Soaking clothes in cold water for 24 hours (without detergent) killed all adults and nymphs, but killed no eggs. Unfortunately, the researchers did not test whether soaking clothes in cold soapy water for 24 hours would kill eggs. This alternative treatment might be useful, especially for cleaning clothes that are labeled for cool wash and dry only.
- Dry cleaning killed all life stages of bed bugs, and would be an appropriate treatment for delicate and temperature-sensitive fabrics.
- When washing clothes, wash water at 60°C (140°F) on 30-minute wash cycles killed 100 percent of all life stages. Washing at 40°C (100°F) killed all adults and nymphs, but only 25 percent of eggs. So clearly, washing clothes for bed bug disinfestation should be done at the hottest temperatures (about 140°F).
Final Thoughts. Experience with many pests verifies the wisdom of using multiple control tactics to control pests — a basic tenet of IPM. Certainly bed bugs are no exception. Reducing clutter, systematic inspection and treatment of the bedroom and other infested rooms, trapping and ongoing monitoring, and effective treatment of all exposed household articles, including clothing, are all essential components of good bed bug control. This research should help all of us with fabric disinfestation.
The author has been an entomology specialist for Texas AgriLife Extension since 1989. Contact him via e-mail at firstname.lastname@example.org.