Bed bugs are parasite usually feed on humans when their preys are unavailable. These blood-sucking parasites can make you uncomfortable during your sleep. Their lifespan varies according to the temperature they are lived with it. It can survive under a cold condition below 16-degree Celsius and can survive on low humidity and a 35–40 °C range even with the loss of one-third of body weight. In the case of adult buds, it can survive for a year without food. They prefer exposed areas of a sleeping person. The bite usually shows a swelling with no red spot, but when many bugs fed on a small area, reddish spots may appear after the swelling subsides. Bed bugs are attracted to their hosts mainly by carbon dioxide, secondarily by warm, some may attract through chemicals but bed bugs can't survive high concentrations of carbon dioxide for very long. If a bed bug completes its feeding, it relocates to a place close to a known host, commonly in or near beds or couches. .