Bedbugs (Cimex lectularis) are 4-5 mm ovoid, flat, wingless, red-brown, nocturnal, blood-sucking insects. The insects hide during the day in the seams of mattresses, in the crevices of box springs, and in the cracks of floors and walls. Bedbugs require a blood meal to progress in their life cycle. The insects feed weekly and prefer to bite in the predawn hours. While a blood meal is required to advance in the life cycle, bedbugs have been known to survive up to 12 months without a blood meal. In the absence of a human host, bedbugs may feed on other animals. The bedbug can travel by concealing itself or its eggs within the dark recesses of suitcases and other personal effects, including clothing.

Bedbugs have afflicted humans for thousands of years but became uncommon after World War II because of widespread use of modern insecticides. Beginning in 1995, a resurgence in bedbug infestations was noted, with rates almost doubling annually in North America, Western Europe, and Australia.

Increased national and international tourism, changes in pesticide use (including a prohibition on DDT), and use of recycled mattresses are thought to contribute to this epidemic of bedbug activity. Contrary to popular belief, cleanliness and hygiene have little impact on bedbug infestation. The insects are attracted to humans based on temperature and carbon dioxide production. Bedbugs are most prevalent in urban areas, likely due to population density and/or crowding.

At present, it is not believed that bedbugs are important vectors of disease transmission, such as human immunodeficiency virus (HIV) or hepatitis B or C. Patients with bedbug bites often come to medical attention seeking relief of resultant pruritus and skin lesions.