Adult bed bugs are light brown to reddish-brown, flattened, oval-shaped and have no hind wings, but front wings are vestigial and reduced to pad-like structures. They 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. Newly hatched nymphs are translucent, lighter in color and become browner as they molt and reach maturity. Bed bugs may be mistaken for other insects, such as booklice, small cockroaches, or carpet beetles, however when warm and active, their movements are more ant-like, and like most other bugs, they emit a characteristic disagreeable odor when crushed.
As the female bed bug lays her eggs (i.e., one to five per day and 200-500 within her lifetime); she uses a clear substance to attach them in cracks and on rough surfaces. Under ideal conditions, eggs hatch in about seven days and the nymphs molt five times, taking a blood meal between each molt. Development time from egg to adult is 21 days. The adult can live for almost one year.
The bed bug hides in cracks and crevices during the day, preferring to rest on wood and paper surfaces instead of stone and plaster. It leaves these harborage areas at night to feed on its host, which include humans, birds, hogs, and family pets. The blood meal requires three to ten minutes and usually goes unnoticed by the victim. After feeding, the bite site may become inflamed and itch severely in sensitive people. Although the bed bug has been associated with over 25 diseases, transmission has not been conclusively proven. Over time, the harborage areas become filled with the molted skins, feces, and old egg shells of the resident bed bugs. These areas have a characteristic “stick bug” smell caused by secretion emitted by the bed bug.