Jeffrey Hahn, Asst. Extension Entomologist
Photo 1. Bed bug biting. Jeff Hahn
This has been one of the coldest winters in Minnesota in 15 years. And while it can be challenging to find many good things to say about this kind of weather, many people take consolation that the cold temperatures are good for killing insect pests. The most common question lately has been whether putting out furniture or other articles in very cold weather will kill bed bugs.
Photo 2: Fluctuating, cold temperatures may not reliably kill bed bugs. Jeff Hahn
Cold temperatures can kill bed bugs if they are exposed to it long enough and at temperatures that are cold enough. However, there is not a lot research on this topic to say what those exposures and temperatures are. What information is available is contradictory. One researcher in 1966 found that bed bugs can tolerate temperatures around 5o F for a brief time and when acclimated can survive temperatures at or below 32o F for days. This is in contrast to findings in 1991 that bed bugs are killed when exposed to temperatures around 32o F for just hours, although the same article also went on to say that the eggs are very cold tolerant and need to be exposed to freezing temperatures for 30 to 60 days.
There is even less research that looks at how long you need to freeze bed bugs when they are in furniture or other objects. The U.S. military believes that if you expose furniture to 0o F or less for four days or more, that may be sufficient. While we have been at or below 0o F often, those temperatures have generally fluctuated and have infrequently been sustained for four days or more.
There are other factors to consider. First, the temperature where the bed bugs are hiding may not be as cold as you think it is, i.e. the air temperature is not necessarily the same where the bed bugs are located in the furniture. You also need to factor in the effect of the sun shining on any objects. Although the temperature may say 0o F, the warmth of the sun can considerably raise the temperature in localized areas (as recently witnessed by the melting snow on my roof in near 0o F temperatures).
Again, cold can kill bed bugs, but the bottom line is you can not reliably kill all bed bugs infesting objects by exposing them to 0o F temperatures.
However, if you have or are concerned that you have items that are infested with bed bugs, keeping them outdoors will certainly immobilize any that are present until you decide what to do with them. If you have clothes, you can reliably kill bed bugs by washing or drying them at the highest temperatures allowed by the fabric. If you have other items you are not sure what to do with, contact an experienced pest control service for help in eradicating the bed bugs.