The suggestion that bed bug (Cimex spp.; Hemiptera: Cimicidae)-infested mattresses wrapped in black plastic and exposed to sunlight will be heated sufficiently to kill the bed bugs was tested. Two types of mattresses were tested: a thin mattress of solid foam rubber and a thick multilayered inner spring mattress. Temperature probes were placed on both upper and lower sides of the mattresses, which were wrapped in black plastic and placed outside on a summer day for >9 h wherein the ambient temperature peaked at 36.5°C. The maximum recorded temperature on the upper (sun-exposed) sides was 85°C for both mattresses, whereas lower side temperatures for the thick mattress never exceeded 35°C, and some areas of the thin mattress failed to exceed 36.5°C. Therefore, with published thermal death points of 40–45°C depending on exposure time, and opportunities for bed bugs to avoid lethal temperatures by retreating from hot zones, this technique seems to be not suitable for bed bug management.