Bedbug bites may go unnoticed or be mistaken for flea or mosquito bites or other types of rash or skin conditions, since the signs of bedbug bites are difficult to distinguish from other bites or skin conditions. Bedbugs also have glands whose secretions may leave musty odors, and they also may leave dark fecal spots on bed sheets and around places where they hide (in crevices or protected areas around the bed or anywhere in the room).
In the lab we handle all the bed bugs in a specific room that we steam clean once a week, and we have double-stick tape barriers that they can't walk through (as long as the adhesive remains dust-free). And the bed bugs themselves are enclosed in containers that they can't get out of. We actually feed them inside those containers—we lay a blood reservoir against the cloth "lid" and the bed bugs have to push their mouthparts through the cloth into the reservoir to eat.
Symptoms may not appear until some days after the bites have occurred. Reactions often become more brisk after multiple bites due to possible sensitization to the salivary proteins of the bed bug. The skin reaction usually occurs in the area of the bite which is most commonly the arms, shoulders and legs as they are more frequently exposed at night. Numerous bites may lead to an erythematous rash or urticaria.
Bed bugs usually bite people at night while they are sleeping. Hungry bed bugs may also feed during the daytime, especially if this is when the occupant normally sleeps. They feed by piercing the skin with an elongated beak through which they withdraw blood. Engorgement of the bed bug takes roughly three to 10 minutes, but because the bite is painless, the person seldom realizes they are being bitten. Bed bugs normally do not reside on people like head or body lice do; instead, immediately after feeding, bed bugs crawl to a secluded location to digest their meal. Symptoms after being bitten by bed bugs vary from person to person. Many develop an itchy red welt within a day or so of the bite. Others have little or no reaction. Sometimes the reaction is delayed days or even weeks after the actual bite occurs, which can make it difficult to determine where or when bites actually occurred. Studies conducted in bed bug-infested apartments suggest about 30 percent of people do not react even when bitten repeatedly over time, and there is still higher incidence of non-reactivity among the elderly. Unlike flea bites, which occur mainly around the lower legs and ankles, bed bugs feed on any skin exposed while sleeping (face, neck, shoulders, back, arms, legs, etc.). The welts and itching are often wrongly attributed to other causes, such as mosquitoes. For these reasons, infestations may go a long time unnoticed, and can become quite large before being detected.
Bites on dogs and cats will look much like bites on people, and the pet owner may actually suspect a mosquito or flea bit the pet. As with people, bed bugs do not stay on pets, but return to a protected harborage site after feeding. In addition to bites, the presence of the bug’s feces, cast skins and the animal’s irritation at night are also indicators of bed bugs biting pets. Therefore, one of the best things to do is inspect the pet’s bedding and frequently groom the animal while being vigilant for the telltale signs of bed bug presence.