What’s the best way to kill bed bugs?

Bed bugs can’t handle the heat. Adults start tapping out around 118°F, eggs need a bit more. But crank it to 122°F+ and it’s lights out for the whole crew. That’s why pros bring the big heaters - DIY just leaves bugs laughing. And when heat’s not the move, pros have chemical playbooks too - sprays, dusts, and regulated treatments that reach the sneaky spots heat can’t. Bottom line: you need the arsenal, not a can of grocery-store bug spray and a prayer.

The Extension Department at Virginia Tech has excellent information on this topic.  https://www.pubs.ext.vt.edu/ENTO/ento-583/ento-583.html 

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It is very important to know, that the thermal death point for bed bug adults and nymphs is 118o F degrees, but the thermal death point for bed bug eggs is 122o F. While bed bugs can be killed when exposed to slightly lower temperatures, (112o- 115o F), they have to consistently be exposed to these temperatures for a number of hours in order for death to occur. Bed bug exposure to lethal temperature is very important to consider when you know that many bugs will hide in cracks and crevices. Therefore, these cracks and crevices must reach 122o F for the heat treatment to be effective. Many heat treatment technicians aim to get the ambient temperature up to 135o F and then leave the heaters in place for four to five hours. They do this under the assumption that the multiple hour treatment will allow all cracks and crevices to get up to bed bug lethal temperature.

However, if it very important to keep in mind that ambient temperature (the temperature of the heated air in the home) is not relevant! Bed bugs are not flying in the air, and the ambient temperature is no predictor of the temperature at floor-wall junctions, or the spaces underneath baseboards. So, it is very important that efforts are made throughout the heat treatment to ensure that all hard-to-heat cracks and crevices are reaching 122o F. Several studies have shown that unless the technician is measuring the temperature in specific areas and adjusting his/her equipment to address hard-to-heat locations, these areas may never make it up to bed bug lethal temperature during the course of a 4–5-hour treatment. In fact, the technician will have to measure temperatures and rearrange the heaters and fans frequently to make sure that all the hard-to-heat locations are reaching lethal temperature.