The bed bug (Cimex lectularius) has been a parasite of humans throughout written history. Its adaptation to humans is so complete that its bite is not noticed until well after the bug leaves its victim, if it is noticed at all. Attracted by the warmth of our bodies and the carbon dioxide we exhale, bed bugs emerge usually at night from hiding places, seeking human blood. While pathogens have been found in bed bugs, the bed bug apparently does not transmit diseases to humans.
Prior to the widespread use of synthetic insecticides, this small, brown blood-sucking bug was perhaps the most unwanted pest in America. The insidious bed bug was loathed even more than the cockroach. Although the bugs impact was greatly reduced by insecticides during the 1940s and 1950s, it remained an occasional invader of homes, hotels and shelters. Pest management professionals now agree that bed bugs have become the most difficult pest to control.
Bed bugs (Cimex spp.) feed on the blood of animals including people and pets. Some species, known as bat bugs, feed on bats, and others on birds such as chickens, pigeons, swallows and swifts. All will wander in search of a new host if their primary host leaves or abandons its roost or nest. In structures, bat bugs typically appear in and around attics and chimneys. Though they will bite humans, they do not survive without their preferred hosts.
Bed bugs can survive more than a year without feeding, but most adults and nymphs probably do not live more than six months without a meal. This ability lets them wait for transient hosts that periodically inhabit camp cabins, apartments and temporary housing. It also helps them survive transportation. Today, bed bugs hitchhike more easily than ever, via public transportation and luggage, and in secondhand furniture, mattresses, bedding and clothing. In multi-unit buildings, bed bug infestations that are not adequately attended to often spread between units with or without human help, making eradication much more difficult and costly.
Most people have never seen a bed bug. Adults are wingless, about one-fourth of an inch long, and flat to fit in cracks and crevices where they hide by day. Females typically lay three to five adhesive eggs per day in crevices and depressions. Eggs and newly hatched nymphs are somewhat translucent and only about one-sixteenth of an inch long. After feeding, nymphs become bright red.
At night, bed bugs seek warm hosts, leaving their hiding places in mattresses, box springs, bed frames, nightstands, curtains, couches and wall voids, baseboards, carpet edges, door and window frames, picture frames, smoke detectors, electrical switches and outlets, peeling paint and wallpaper.
BED BUG BITES
The bed bug painlessly bites its victim, injects saliva to ensure blood flow, and ingests the hosts blood through needle-like mouthparts. During the three to five minutes it takes to complete feeding, the bug elongates and becomes more reddish. It then retreats to its hiding place to digest the meal, and will return to feed in three to 10 days.
Reactions to bed bug bites vary among individuals. Many persons show no signs of bites. Others dont realize theyve been bitten until redness and swelling appear around the bite, sometimes with intense itching. Some exhibit inflamed swollen spots that may occur in linear series or have a rash-like appearance. Such bite marks, when they appear, may not show for several days after the person is bitten.
SIGNS OF BED BUGS
Continued here:
Bed Bugs Prevention and Control - Illinois Department of Public Health
Residence 
Location 
