Adult bed bugs are light brown to reddish-brown, flattened, oval-shaped and have no hind wings. The front wings are vestigial and reduced to pad-like structures. Bed bugs have segmented abdomens with microscopic hairs that give them a banded appearance. Adults grow to 4–5 mm in length and 1.5–3 mm wide.
Bed bugs are obligatory hematophagous (bloodsucking) insects. Most species feed on humans only when other prey are unavailable. They obtain all the additional moisture they need from water vapor in the surrounding air. Bed bugs are attracted to their hosts primarily by carbon dioxide, secondarily by warmth, and also by certain chemicals.
Their bites are not usually noticed at the time. They develop slowly to low itchy welts that may take weeks to go away. They prefer exposed skin, preferably the face, neck and arms of a sleeping individual. The neck and jaw line are particularly favored places to feed.
Though commonly used, the pesticide approach often requires multiple visits and may not always be effective due to pesticide resistance and dispersal of the bed bugs. According to a 2005 survey, only 6.1% of companies claim to be able to eliminate bed bugs in a single visit, while 62.6% claim to be able to control a problem in 2–3 visits. Insecticide application may cause dispersal of bed bugs to neighbouring areas of a structure, spreading the infestation. Furthermore, the problem of insecticide resistance in bed bug populations increases their opportunity to spread. Studies of bed bug populations across the United States indicate that resistance to pyrethroid insecticides, which are used in the majority of bed bugs cases is widespread. Exterminators
often require individuals to dispose of furniture and other infested materials. It is advisable to break or mark these infested items to prevent their being unintentionally recycled and furthering the spread of bed bugs.