Bedbugs or bed bugs are small parasitic insects of the family Cimicidae (most commonly 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. The name ‘bedbug’ is derived from the insect’s preferred habitat of houses and especially beds or other areas where people sleep. Bedbugs, though not strictly nocturnal, are mainly active at night and are capable of feeding unnoticed on their hosts.
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.
Bedbugs have been known by a variety of names including wall louse, mahogany flat, crimson rambler, heavy dragoon, chinche, and redcoat.Largely eradicated as pests in the developed world in the early 1940s, bedbugs have seen a resurgence since about 1995.
Adult bedbugs are reddish-brown, flattened, oval, and wingless. Bedbugs 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.
Bedbugs use pheromones and kairomones to communicate regarding nesting locations, attacks, and reproduction.
The life span of bedbugs varies by species and is also dependent on feeding.
Bedbugs 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. Bedbugs 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). Bedbugs 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.
Bedbugs are obligatory hematophagous (bloodsucking) insects. Most species feed on humans only when other prey are unavailable. Bedbugs are attracted to their hosts primarily by carbon dioxide, secondarily by warmth, and also by certain chemicals.
A bedbug pierces the skin of its host with two hollow feeding tubes. 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.
Although bedbugs can live for a year without feeding, they normally try to feed every five to ten days. In cold weather, bedbugs 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, it was reported that newer generations of pesticide-resistant bedbugs in Virginia could 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 bed bugs to be used for forensic purposes for identifying who the bed bugs have been feeding on.
All bedbugs mate by traumatic insemination. Because the female has no genital opening, the male pierces her abdomen with his hypodermic genitalia and ejaculates into the body cavity. Male bedbugs sometimes attempt to mate with other males and pierce the latter in the abdomen.
The “bedbug alarm pheromone” consists of (E)-2-octenal and (E)-2-hexenal. It is released when a bedbug is disturbed, as during an attack by a predator. A 2009 study demonstrated that the alarm pheromone is also released by male bedbugs to repel other males who attempt to mate with them.
C. lectularius and C. hemipterus will mate with each other given the opportunity, but the eggs then produced are usually sterile. In a 1988 study, 1 egg out of 479 was fertile and resulted in a hybrid, C. hemipterus × lectularius.
Bedbugs have six life stages (5 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. Bedbugs must molt six times before becoming fertile adults.
A number of health effects may occur due to bedbugs including skin rashes, psychological effects and allergic symptoms. Bedbug bites or cimicosis may lead to a range of skin manifestations from no visible effects to prominent blisters. Diagnosis involves both finding bedbugs and the occurrence of compatible symptoms. Treatment involves the elimination of the insect but is otherwise symptomatic.
Because infestation of human habitats has been on the increase in developed countries, bedbug bites and related conditions have been on the rise as well, since the 1980s-1990s. 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 bedbug countermeasures, and increasing resistance to pesticides. Bedbugs have been known human parasites for thousands of years.
Dwellings can become infested with bedbugs in a variety of ways:
* from bugs and eggs that “hitchhiked in” on clothing and luggage,
* from infested items (e.g., furniture, clothes) brought in,
* from a nearby dwelling or infested item, if there are easy routes, or
* from wild animals (e.g. bats, birds) and pets brought in.
Bedbugs can be found on their own 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. Bedbugs may also nest near animals that have nested within a dwelling, such as bats, birds, or rodents.
Bedbugs are elusive and usually nocturnal, which can make them hard to spot. Bedbugs 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 moults.
Attractant devices for detection use heat and/or carbon dioxide.
Bed bug detection dogs are trained to pinpoint infestations, with an accuracy of 97.5%, and often in minutes where a pest control practitioner might need an hour. In the United States, about 100 dogs are used to find bedbugs as of mid-2009.
Eradication of bedbugs 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.
The carbamate insecticide propoxur is highly toxic to bedbugs, but the Environmental Protection Agency (EPA) has been reluctant to approve such an indoor use because of its potential toxicity to children after chronic exposure.
Bedbugs are developing resistance to various pesticides including DDT, and organophosphates.
Some populations have developed a resistance to pyrethroid insecticides, there is growing interest in both synthetic pyrethroid and pyrrole insecticide chlorfenapyr; insect growth regulators such as hydroprene (Gentrol) are sometimes used.
Populations in Arkansas have been found to be highly resistant to DDT, with an LD50 of more than 100,000 PPM  DDT was seen to make bedbugs more active in studies done in Africa.
Bedbug pesticide-resistance appears to be increasing dramatically. Bedbug populations sampled across the U.S. showed a tolerance for pyrethroids several thousands of times greater than laboratory bedbugs. New York City bed bugs have been found to be 264 times more resistant to deltamethrin than Florida bedbugs due to nerve cell mutations.
A population genetics study of bed bugs in the United States, Canada, and Australia using a mitochondrial DNA marker found high levels of genetic variation. This suggests that the studied bed bug populations did not undergo a genetic bottleneck as one would expect from insecticide control during the 1940s and 1950s, but instead, that populations may have been maintained on other hosts such as birds and bats. In contrast to the high amount of genetic variation observed with the mitochondrial DNA marker, no genetic variation in a nuclear rRNA marker was observed. This suggests increased gene flow of previously isolated bed bug populations, and given the absence of barriers to gene flow, the spread of insecticide resistance may be rapid.
Natural enemies of bedbugs include the masked hunter (also known as “masked bedbug hunter”), cockroaches, ants, spiders, mites, and centipedes. The Pharaoh ant’s (Monomorium pharaonis) venom is lethal to bedbugs. Biological pest control is not very practical for eliminating bedbugs from human dwellings.
Main article: Epidemiology of bedbugs
Bedbugs occur around the world. Rates of infestations in developed countries while decreasing from the 1930s to the 1980s have increased dramatically since the 1980s. Previous to this they were common in the developing world but rare in the developed world. The increase in the developed world may have been caused by increased international travel, resistance to insecticides, and the use of new pest-control methods that do not affect bedbugs. The fall in bedbug populations after the 1930s in the developed world is believed to be partly due to the usage of DDT to kill cockroaches. The invention of the vacuum cleaner and simplification of furniture design may have also played a role. Others believe it might simply be the cyclical nature of the organism.
The common bedbug (Cimex lectularius) is the species best adapted to human environments. It is found in temperate climates throughout the world. Other species include Cimex hemipterus, found in tropical regions, which also infests poultry and bats, and Leptocimex boueti, found in the tropics of West Africa and South America, which infests bats and humans. Cimex pilosellus and Cimex pipistrella primarily infest bats, while Haematosiphon inodora, a species of North America, primarily infests poultry.
Bedbugs were mentioned in ancient Greece as early as 400 BC (later mentioned by Aristotle). Pliny’s Natural History, first published c. 77 AD in Rome, claimed that bedbugs had medicinal value in treating ailments such as snake bites and ear infections. (Belief in the medicinal use of bedbugs persisted until at least the 18th century, when Guettard recommended their use in the treatment of hysteria.) Bedbugs 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. It was believed by some in the 18th century that bedbugs 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.
Prior to the mid-twentieth century, bedbugs 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 bedbug infestation.
Bedbugs were a serious problem during World War II. General McArthur commented that bedbugs are the “greatest nuisance insect problem … at bases in the U.S