Bed bugs are parasitic insects of the cimicid family that feed exclusively on blood. Cimex lectularius, the common bed bug, is the best known as it prefers to feed on human blood; other Cimex species specialize in other animals, e.g., bat bugs, such as Cimex pipistrelli (Europe), Cimex pilosellus (Western United States), and Cimex adjunctus (entire Eastern United States).
The name bed bug derives from the preferred habitat of Cimex lectularius: warm houses and especially near or inside beds and bedding or other sleep areas. Bed bugs are mainly active at night, but are not exclusively nocturnal. They usually feed on their hosts without being noticed.
A number of adverse health effects may results from bed bug bites, including skin rashes, psychological effects, and allergic symptoms. Bed bugs are not known to transmit any pathogens as disease vectors. Certain signs and symptoms suggest the presence of bed bugs; finding the adult insects confirms the diagnosis.
Bed bugs have been known as human parasites for thousands of years. At a point in the early 1940s, they were mostly eradicated in the developed world, but have increased in prevalence since 1995, likely due to pesticide resistance, governmental bans on effective pesticides, and international travel. Because infestation of human habitats has begun to increase, bed bug bites and related conditions have also been on the rise.
Diagnosis of an infestation involves both finding bed bugs and the occurrence of compatible symptoms. Treatment involves the elimination of the insect (including its eggs) and taking measures to treat symptoms until they resolve.
Although bed bugs can be infected with at least 28 human pathogens, no studies have found that the insects are capable of transmitting any of these to humans. They have been found with methicillin-resistant Staphylococcus aureus (MRSA) and with vancomycin-resistant Enterococcus faecium (VRE), but the significance of this is still unknown.
Investigations into potential transmission of HIV, MRSA, hepatitis B, hepatitis C, and hepatitis E have not found any evidence that bed bugs can spread these diseases. However, arboviruses may be transmissible.
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. Bedbugs prefer exposed skin, preferably the face, neck, and arms of a sleeping person.
Bedbugs have mouth parts that saw through the skin, and inject saliva with anticoagulants and painkillers. Sensitivity of humans varies from extreme allergic reaction to no reaction at all (about 20%). The bite usually produces a swelling with no red spot, but when many bugs feed on a small area, reddish spots may appear after the swelling subsides.
Although under certain cool conditions adult bed bugs can live for over a year without feeding, under typically warm conditions they try to feed at five- to ten-day intervals, and adults can survive for about five months without food. Younger instars cannot survive nearly as long, though even the vulnerable newly hatched first instars can survive for weeks without taking a blood meal.
DNA from human blood meals can be recovered from bed bugs for up to 90 days, which means they can be used for forensic purposes in identifying on whom the bed bugs have fed.