University of Florida researchers have published their study of heat treatments to control bed bug infestations (free PDF). What distinguishes their approach from other published accounts is the DIY character of their method and materials: space heaters, fans, polystyrene boards, thermometers. All of $300.
As opposed to whole-room or chamber heat treatments, which necessitate expensive specialized equipment, their aim was to use heat to economically treat infested furniture by creating a heat envelope, an area within a room where, with the aid of inexpensive insulating materials, temperatures could rise to lethal levels—moderately high temperatures are sufficient—and then to use residual treatments in areas outside the envelope where heat could not penetrate. This point is important to understand and stands as my only caveat; bed bugs placed in control vials in closets or areas away from the heat definitely survived.
(It’s no secret that desperate bed bug sufferers do desperate things. Others have noted the ineffective and counterproductive measures frequently taken. Given the possibility that you might rush off to Home Depot without thinking things through, I worried about having to say many responsible things, but you can read for yourself. If you’re capable enough to pull this off on your own, good for you. If you’re not but think that you are, then no warning from me is going to deter you.)
This is the article and at the moment it’s available as a free download here.
Pereira, Roberto M.; Koehler, Philip G.; Pfiester, Margie; Walker, Wayne (2009) Lethal Effects of Heat and Use of Localized Heat Treatment for Control of Bed Bug Infestations. Journal of Economic Entomology. 102(3). 1182-1188. doi: 10.1603/029.102.0342
For the purposes of these experiments, the fact that the heat did not penetrate areas outside the envelope was judged an advantage:
Despite generating temperatures well above the lethal levels for bed bugs (41–49°C) within the treatment envelope, the heat treatment did not elevate the room temperature to temperatures >32°C (Table 3). Maintaining the room temperature at comfortable levels for human activity is very important because the heat treatment is intended to supplement a residual pesticide applied to the baseboard and other potential resting areas for bed bugs. Such treatment could be applied while the room furniture is exposed to heat treatment.
I’m not sure how much it helps to kill the bed bugs in the sofa (even if they might be the hardest to kill of all) but still have bed bugs under the window sill, but if a war of attrition is all there is against these bugs, so be it.
I appreciate the discussion of what failed and I hope those of you interested in this solution will study this closely.
The bed bugs placed in different locations during the treatments had 100% mortality for all but two trials: the first trial (room D) and the initial trial in room Yb, both in rooms with tile floors. The initial treatment trial never produced lethal temperatures for the bed bugs in any location where temperature was measured. The maximum temperature reached was 41.5°C after 6.3 h, and the total treatment period was 7.3 h, indicating that the temperature in the treatment envelope did not rise during the last hour. This stabilization of the temperature was due to the excessive heat loss through the plastic tarp and the tile floor. Once polystyrene sheathing boards were used as the insulation around the treated furniture, the heat loss was significantly reduced and temperatures continued to increase throughout the treatments.
Yet more interesting are the boundaries of what was investigated:
These results demonstrate that short exposures to temperatures above 41°C will cause temporary immobilization of bed bugs, even when lethal levels were not reached. Once the bed bugs’ exposures to high temperatures were interrupted, some insects were able to survive. We did not test long-term survival of the heat-exposed bed bugs and did not determine whether survivors’ fitness was compromised. Bed bugs that survived exposures to nonlethal temperatures have been shown to have reduced fitness (Janisch 1933, 1935, cited by Johnson 1941). Sublethal effects of high temperatures are documented for several insects (Neven 2000, Mahroof et al. 2005). However, thermal wounding by sublethal temperatures may be as deadly, but without obvious effects that lethal temperatures cause (Denlinger and Yocum 1998).
These experiments were conducted in University of Florida dorms and campus housing, a convenience that has been exploited before.
1924
In 1924, at the Agricultural and Mechanical College of Mississippi, bed bugs were successfully treated by simply turning on the dormitory building’s steam heat in the summer (average high temperatures of 115.8°F produced 100% mortality). This of course has nearly always been regarded as impractical.
The question of sublethal effects is an interesting one. In the Mississippi experiments, monitor boxes containing live bed bugs were placed in some of the rooms. Here’s an account of the fate of those bed bugs in one room:
In another room, most of the bugs were alive at 8 A. M. of the first day when the temperature had reached 108 degrees. At 1 P. M., with the temperature at 111 degrees, a few were found paralyzed; at 5 P. M., with the temperature at 114 degrees, all were apparently dead and the box was then removed. Several days later, the contents of the box was re-examined. At this time, 6 nymphs and 5 adults were dead but 3 nymphs were found to be alive, though paralyzed. Twelve days after removing from the heated room, the contents of the box were again examined and all were found to be dead, the paralyzed nymphs having failed to recover.
Dead, recovered, dead again. Nice.
Harned, R.W., Allen, H.W. (1925) Controlling Bedbugs in Steam-Heated Rooms. Journal of Economic Entomology. 18(2). 320-331.
While we’re here visiting the 20s, there’s a small joke in this article that we may as well examine for what it reveals of the polite bed bug fictions of the day (making me wonder what our own are today).
The authors describe the dormitory as one where many rooms “were found to be heavily infested with living bugs.” The paper must have been presented and a portion of the discussion transcribed with the article as there is a brief Q&A at the end:
MR. L. O. HOWARD: [...]
I have never been at the Agricultural College of Mississippi, but I had the pleasure of meeting a group of Professor Harned’s former students a year and a half ago at Gulfport at a dinner, and I saw the extraordinary love and admiration that they have for him. But it seems to me, assuming that this large dormitory could not have become naturally infested by bedbugs, that it must have been a part of a large experiment of introducing bedbugs in which the whole student body was concerned. From that point of view, it strikes me as one of the most extraordinary pieces of cooperation on record. (Laughter.)
UF’s research showcase
The University of Florida has a showcase document for their research, a bed bug manual of sorts that is well worth a look. You get to see useful pictures of the heat experiments, lots of information and recommendations on fumigation (Vikane), the armed forces’ technical guide on bed bugs included, plus a PCT article on the UF bed bug management method, Fumigation, Steam, Dusting and Labor, Walker et al. and a number of interesting slides.
If perhaps you’ve always wondered how fast bed bugs may crawl, or what exactly is meant about their missing tarsal pads, wonder no more. Here’s a link to the PDF and this is the page at the University of Florida. (The PDF is a large file, 100 pages.)
Further heat reading
There are also two 2008 PCT articles about heat trials if you wish to read further and compare notes, one from University of Kentucky researchers, Bed Bugs, Heat and Hotel Rooms, Potter et al. and another from a UC Berkeley group, Hot House, Getty et al.
Update: Doug Summers in a comment notes a safety caution:
I would like to caution anyone who is thinking about using this approach to consider using a proper commercial heater, instead of the residential style 1500 watt portable oil units that were utilized in the study.
The issue is fire safety… If you enclose the heater with insulated panels then you have voided the warranty… There was an extensive recall of this style of heater a few years ago… They were causing fires due to a faulty override switch that should switch the heater off at 130 degrees F.
