Bed bugs, bed-bugs, or bedbugs are parasitic insects of the cimicid family that feed exclusively on blood. Cimexlectularius, the common bed bug, is the best known as it prefers to feed on human blood although other Cimex species are specialized to other animals, e.g., bat bugs, Cimexpipistrelli (Europe), Cimexpilosellus (western US), and Cimexadjunctus (entire eastern US).

The name of the “bed bug” is derived from the preferred habitat of Cimexlectularius: warm houses and especially nearby or inside of 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 result from bed bug bites, including skin rashes, psychological effects, and allergic symptoms.

They are not known to transmit any pathogens as disease vectors. Certain signs and symptoms suggest the presence of bed bugs; finding the 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.

Because infestation of human habitats has been on the increase, bed bug bites and related conditions have been on the rise as well.

Cause

Dwellings can become infested with bed bugs in a variety of ways, such as:
• Bugs and eggs inadvertently brought in from other infested dwellings on a visiting person’s clothing or luggage;
• Infested items (such as furniture, clothing, or backpacks) brought in;
• Nearby dwellings or infested items, if easy routes are available for travel, e.g. through ducts or false ceilings;
• Wild animals (such as bats or birds) that may also harbour bed bugs or related species such as the bat bug;
• People visiting an infested area (e.g. dwelling, means of transport, entertainment venue, or lodging) and carrying the bugs to another area on their clothing, luggage, or bodies. Bedbugs are increasingly found in air travel.

• Though bed bugs will feed on pets, they do not live or travel on the skin of their hosts, and pets are not believed to be a factor in their spread

Physical

• Adult bed bugs are light brown to reddish-brown, flattened, oval-shaped and have no hind wings. The front wings are vestigial and reduced to pad-like structures. Bed bugs have segmented abdomens with microscopic hairs that give them a banded appearance. Adults grow to 4–5 millimetres (0.16–0.20 in) long and 1.5–3 millimetres (0.059–0.118 in) wide.

• Newly hatched nymphs are translucent, lighter in color and become browner as they moult and reach maturity. A bed bug of any age that has just consumed a blood meal will have a bright red translucent abdomen, fading to brown over the next several hours, and to opaque black within two days as the insect digests its meal. 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 true bugs, they emit a characteristic disagreeable odor when crushed.

• Bed bugs use pheromones and kairomones to communicate regarding nesting locations, feeding and reproduction.

• The life span of bed bugs varies by species and is also dependent on feeding.

• Bed bugs can survive a wide range of temperatures and atmospheric compositions. Below 16.1 °C (61.0 °F), adults enter semi-hibernation and can survive longer; they can survive for at least five days at -10 °C (14 °F), but will die after 15 minutes of exposure to -32 °C (-26 °F).

Common commercial and residential freezers reach temperatures low enough to kill most life stages of bed bug, with 95% mortality after 3 days at -12 °C (10 °F).

They show high desiccation tolerance, surviving low humidity and a 35–40 °C range even with loss of one-third of body weight; earlier life stages are more susceptible to drying out than later ones.

• The thermal death point for Cimexlectularius is 45 °C (113 °F); all stages of life are killed by 7 minutes of exposure to 46 °C (115 °F).
Bed bugs apparently cannot survive high concentrations of carbon dioxide for very long; exposure to nearly pure nitrogen atmospheres, however, appears to have relatively little effect even after 72 hours

CDC 11739 Cimex lectularius SEM” by Janice Harney Carr, Center for Disease Control

• Feeding habits

• 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 will 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.
• At the 57th annual meeting of the Entomological Society of America in 2009, newer generations of pesticide-resistant bed bugs in Virginia were reported to survive only two months without feeding.

• DNA from human blood meals can be recovered from bed bugs for up to 90 days, which may allow them to be used for forensic purposes in identifying on whom the bed bugs have been feeding.