One bed bug will usually take more than one bite. Once a bed bug inserts its mouthparts and finds a suitable blood vessel, it will begin feeding. However, finding the right blood vessel may take more than one injection into the skin. In addition, bed bugs are very sensitive to movement by the host they are feeding on. Therefore, if a sleeping person moves, a feeding bed bug will probably withdraw its mouthparts and begin its search for a blood meal on another part of the body. It’s important to remember that the number of bites a person receives is not indicative of the number of bed bugs that feed on that person.
To avoid light, bedbugs hide in the seams of mattresses and crevices of bed frames, walls, and furniture during the day.5,7 They are attracted to human hosts by warmth and carbon dioxide; these hosts generally sleep within 3 to 7 feet (1 to 2 meters) of the bedbugs’ hiding places.8,9 Feeding usually takes place just before dawn.10 Bedbug saliva contains several anesthetic, vasodilatory, anticoagulant, and proteolytic compounds that allow the insects to feed undetected for five to 10 minutes. Three of these compounds have been identified as instigators of the subsequent hypersensitivity reactions that may be noticed when the host awakens.11–14
In infestations with persistent, repeated exposures, bed bug bites may appear in crops. Also, since bed bug bites usually take three to six weeks to heal, as long as the infestation is still present, new bites may accumulate even as the older ones start to resolve. Thus, people may have various bite reactions in various stages of evolution at the same time.
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.