The first sign of a bed bug problem is obvious: the bed. After bed bugs feed on humans, they'll leave behind blood stains resembling small rust spots. These will usually be found near the corners and edges of the bed. Bed bugs also shed their skin, or molt, several times as they mature, so you may find their oval brown exoskeletons during your search.
Unlike those of other insects, bed bug bites may sometimes appear in tight lines of multiple, small, red marks where multiple bed bugs have fed along an exposed area. Bed bug bites can cause itchiness. Initially, a victim may detect a slight burning sensation. The burning area then develops red bumps, known as papules or wheals (rash). In extreme cases, bites may swell dramatically or turn into blister-like skin inflammations.