The common bedbug is a one-eighth-inch-long, six-legged, reddish brown creature. Like the mosquito, it feeds on blood by painlessly injecting a needlelike mouthpart into its victim's skin. It is typically a nighttime feeder, catching its victims asleep in bed (hence its name) and sensing its prey by either body heat or odor. Allergies to this bug are believed related to the bug's saliva, which it injects into the wound site to liquefy the skin and keep the blood from clotting.

Only one or two bite sites are typically found at a time. The face, arms, and legs the exposed areas are the favored sites of attack. The skin lesions that result are usually itchy round or oval hives that possess a small pinpoint-sized blood spot in the center. Especially susceptible persons may also develop small blisters and areas of eczema. More severe allergic symptoms include the development of widespread hives, asthma, and joint pains.

Bedbugs live in cracks and crevices within furniture and within any dark, insulated home area where they can hide. Like fleas, they can survive as long as one year without feeding. Bedbug infestations may be detected by the peculiar pungent odor in heavily infested dwellings or by identifying bedbug excrement on surfaces such as wallpaper.

As with other kinds of bites and sting reactions, local treatment usually consists of topical corticosteroid creams and oral antihistamines. More widespread reactions may also require oral corticosteroid pills such as prednisone to suppress inflammation. However, to put an end to the problem entirely rather than just treat symptoms, the bug must be rooted out of the home. Malathion- or pyrethrum-containing insecticides have proven effective for this. Unfortunately, because of this bug's incredible ability to hide and its mobility, extermination is often difficult even for professionals.