The bed bug, Cimex lectularius, has recently resurged as a household pest after its near disappearance following World War II. Heat and carbon dioxide have been implicated as important host-finding cues. We investigated the mechanisms of orientation of bed bugs to these cues by placing individuals in a 26cm x 20cm arena with a heat source ranging from room temperature to 50°C. We recorded their movement patterns with video tracking software. More bed bugs found a heat source of 45°C than other tested temperatures. The 50°C treatment resulted in the highest average velocity; however the bugs took longer to reach the heat source. The treatment closest to body temperature, 35°C, resulted in the lowest turning rate as well as the shortest time to the source. The implications of these results for bed bug detection and monitoring will be discussed.