Cimicidae or bed bugs (sometimes bedbugs), are small parasitic insects. The most common type is Cimex lectularius. The term usually refers to species that prefer to feed on human blood. All insects in this family live by feeding exclusively on the blood of warm-blooded animals.
A number of health effects may occur due to bed bugs including skin rashes, psychological effects and allergic symptoms. Diagnosis involves both finding bed bugs and the occurrence of compatible symptoms. Treatment is otherwise symptomatic.
In the developed world, bed bugs were largely eradicated as pests in the early 1940s, however have increased in prevalence since about 1995. Because infestation of human habitats has been on the increase, bed bug bites and related conditions have been on the rise as well. The exact causes of this resurgence remain unclear; it is variously ascribed to greater foreign travel, more frequent exchange of second-hand furnishings among homes, a greater focus on control of other pests resulting in neglect of bed bug countermeasures, and increasing resistance to pesticides. Bed bugs have been known human parasites for thousands of years.
The name "bed bug" is derived from the insect's preferred habitat of houses and especially beds or other areas where people sleep. Bed bugs, though not strictly nocturnal, are mainly active at night and are capable of feeding unnoticed on their hosts.

Description
Physical
Adult bed bugs are reddish-brown, flattened, oval and wingless. Bed bugs have microscopic hairs that give them a banded appearance. Adults grow to 4–5 mm in length and 1.5–3 mm wide. Newly hatched nymphs are translucent, lighter in color and become browner as they moult and reach maturity. Bed bugs may be mistaken for other insects such as booklice and carpet beetles, or vice-versa.
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. Bed bugs can survive for at least five days at −10 °C (14.0 °F) but will die after 15 minutes of exposure to −32 °C (−26 °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 C. lectularius is high: 45 °C (113 °F), and 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.

Feeding habits
Bed bugs are obligatory hematophagous (bloodsucking) insects. Most species feed on humans only when other prey are unavailable. Bed bugs are attracted to their hosts primarily by carbon dioxide, secondarily by warmth, and also by certain chemicals.
A bed bug pierces the skin of its host with two hollow feeding tubes shaped like tongues. With one tube it injects its saliva, which contains anticoagulants and anesthetics, while with the other it withdraws the blood of its host. After feeding for about five minutes, the bug returns to its hiding place. It takes between five to ten minutes for a bed bug to become completely engorged with blood.”
Although bed bugs can live for a year without feeding, they normally try to feed every five to ten days. In cold weather, bed bugs can live for about a year; at temperatures more conducive to activity and feeding, about 5 months.
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 from bed bugs can be recovered for up to 90 days, which may allow them to be used for forensic purposes for identifying on whom the bed bugs have been feeding.

Life stages
Bed bugs have six life stages (five immature and an adult stage). They will shed their skins through a molting process (ecdysis) throughout multiple stages of their lives. The discarded outer shells look like clear, empty exoskeletons of the bugs themselves. Bed bugs must molt six times before becoming fertile adults.

Slide of Cimex lectularius






Bed bug (4 mm length; 2.5 mm width), shown in a film roll plastic container, on the right is the recently sloughed skin from its nymph stage



A bed bug nymph feeding on host





Blood-fed Cimex lectularius (Note the differences in color with respect to digestion of blood meal) Infestation






Dwellings can become infested with bed bugs in a variety of ways, from: Bugs and eggs that "hitchhiked in" on pets,  or on clothing and luggage Infested items (such as furniture or clothing) brought in, nearby dwellings or infested items, if there are easy routes (through duct work or false ceilings),wild animals (such as bats or birds),people visiting from a source of infestation; bed bugs, like roaches, are transferred by clothing, luggage, or a person's body.

Detection



An engorged female bed bug (Cimex lectularius) with eggs, discovered in the screw hole of a wooden bed frame Bed bugs are elusive and usually nocturnal, which can make them hard to spot. They often lodge unnoticed in dark crevices, and eggs can be nestled in fabric seams. Aside from bite symptoms, signs include fecal spots, blood smears on sheets, and molts.
Bed bugs can be found singly, but often congregate once established. They usually remain close to hosts, commonly in or near beds or couches. Nesting locations can vary greatly, however, including luggage, vehicles, furniture and bedside clutter. Bed bugs may also nest near animals that have nested within a dwelling, such as bats, birds, or rodents. The eggs of bed bugs are found in similar places where the bed bugs themselves are found, and are attached to surfaces by a sticky substance.
Attractant devices for detection use heat and/or carbon dioxide.[Bed bugs can be detected by their characteristic smell of almonds or over-ripe raspberries. Bed bug detection dogs are trained to pinpoint infestations, with a possible accuracy rate of 97.5%, based upon tests conducted under controlled conditions by researchers. The success rates in these tests may not reflect real world success rates of a pest companies’ dogs, operating with many more variables in the field.

Eradication of bed bugs frequently requires a combination of pesticide and non-pesticide approaches. Pesticides that have historically been found to be effective include: pyrethroids, dichlorvos and malathion. Resistance to pesticides has increased significantly over time and there are concerns of negative health effects from their use. Mechanical approaches such as vacuuming up the insects and heat treating or wrapping mattresses have been recommended.

There is growing interest in both synthetic pyrethroid and the pyrrole insecticide, chlorfenapyr. Insect growth regulators, such as hydroprene (Gentrol), are also sometimes used. DDT was seen to make bed bugs more active in studies conducted in Africa. New York City bed bugs have been found to be 264 times more resistant to deltamethrin than Florida bed bugs due to nerve cell mutations.

Predators
Natural enemies of bed bugs include the masked hunter (also known as "masked bed bug hunter, cockroaches, ants, spiders (particularly Thanatus flavidus), mites and centipedes.  Biological pest control is not very practical for eliminating bedbugs from human dwellings.

History
C. lectularius may have originated in the Middle East, in caves inhabited by bats and humans. Bed bugs were mentioned in ancient Greece as early as 400 BC, and were later mentioned by Aristotle. Pliny's Natural History, first published circa 77 AD in Rome, claimed bed bugs had medicinal value in treating ailments such as snake bites and ear infections. (Belief in the medicinal use of bed bugs persisted until at least the 18th century, when Guettard recommended their use in the treatment of hysteria. Bed bugs were first mentioned in Germany in the 11th century, in France in the 13th century and in England in 1583, though they remained rare in England until 1670. Some in the 18th century believed bed bugs had been brought to London with supplies of wood to rebuild the city after the Great Fire of London (1666). Giovanni Antonio Scopoli noted their presence in Carniola (roughly equivalent to present-day Slovenia) in the 18th century.
Traditional methods of repelling and/or killing bed bugs include the use of plants, fungi, and insects (or their extracts), such as black pepper, black cohosh (Actaea racemosa), Pseudarthria hookeri, Laggera alata Eucalyptus saligna oil, tobacco, "heated oil of Terebinthina" (i.e. true turpentine), wild mint (Mentha arvensis), Robert geranium (Geranium robertianum), bugbane (Cimicifuga spp.), "herb and seeds of Cannabis", masked hunter bugs (Reduvius personatus), "and many others." In the mid-19th century, smoke from peat fires was recommended. Dusts have been used to ward off insects from grain storage for centuries, including "plant ash, lime, dolomite, certain types of soil, and diatomaceous earth (DE) or Kieselguhr". Of these, diatomaceous earth in particular has seen a revival as a nontoxic (when in amorphous form) residual pesticide for bed bug abatement. Insects exposed to diatomaceous earth may take several days to die. Prior to the mid-twentieth century, bed bugs were very common. According to a report by the UK Ministry of Health, in 1933 there were many areas where all the houses had some degree of bed bug infestation.Bed bugs were a serious problem during World War II. General MacArthur commented that bed bugs are the "greatest nuisance insect problem ... at bases in the U.S” With the arrival of potent pesticides, famously DDT in the 1940s, bed bugs almost disappeared in western countries.However, bed bug infestations have resurged in recent years, for reasons which are not clear, but contributing factors may be complacency, increased resistance and increased international travel. The current wave of bed bug infestations across America has spawned an industry for bed bug prevention, eradication and the reporting of infestations.