Physical methods

Heat treatment. All stages of insects are relatively vulnerable to high temperatures. If it rises just a few degrees above the optimum temperature, development stops and harmful effects occur. Coming up around 50 degrees Celsius the heat kills in a short time. Heat treatment is therefore an obvious control method. Less suspicious effects can be treated in an incubator for example. Just an hour at 50 degrees Celsius will suffice. Of course, it must be made sure that things get thoroughly hot during this period. Heating of rooms may be an option. Here the temperature has to be kept at 50 degrees for at least 12 hours, and attention should be paid to the fact the animals possibly will take refuge in cool crevices. The method is not without problems, and temperature sensors should in all cases be placed at strategic locations.

Cold treatment. As mentioned, bed bugs are sensitive to low temperatures. Normal deep freezer temperatures -18 to -20 degrees Celsius kill them within 3-4 days. It is a reasonable method for treating small batches of suspicious effects when it has been ensured that they can tolerate this treatment.

Non-toxic dusts. Diatomaceous earth and other fine-grained mineral soils have been used for insect control since ancient times. The “Romans” mixed fine road dust in the grain to be stored. Diatomaceous earth acts primarily by destroying the waxy layer that protects the insects from drying out. The effect is relatively slow. The insects die within a week due to water loss. In turn, this dust keeps its effects almost infinitely, if kept dry. Diatomaceous earth is suitable for treating inaccessible cavities and crevices, which can serve as strongholds for the insects.

Modified atmospheres. The principle consists in replacing the ordinary atmospheric air with an air, which is oxygen deficient and contains large amounts of nitrogen or carbon dioxide. In the long run, insects cannot live in an oxygen deficient atmosphere, but the treatment requires a lot of time, often weeks to be effective, something that requires the method to be used in fully sealed containers. Bed bugs are not particularly sensitive to nitrogen, but carbon dioxide has a direct toxic effect like heat and pressure can reduce treatment time significantly.

Biological control. Biological control where the pests’ natural enemies are actively used is a recognized method against many pests in agriculture and forestry. Bed bugs have some natural enemies, the assassin bug (page xx) among others, but their natural amount will never be such that they play a practical role, and the release of large amounts of these reduviids in Danish homes is obviously not an acceptable method of keeping bed bugs at bay.