The common bedbug (Cimex lectularius) is the best adapted to human environments. It is found in temperate climates throughout the world and has been known since ancient times.
Other species include Cimex hemipterus, found in tropical regions (including Florida), 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 C. pipistrella primarily infest bats, while Haematosiphon inodora, a species of North America, primarily infests poultry.
Oeciacus, while not strictly a bedbug, is a closely related genus primarily affecting birds.
Newly hatched bed bug nymphs are translucent and lighter in color than adults. They continue to become browner and molt as they reach maturity. Nymphs go through five stages of growth and can range in size from 1.5 mm to 4.5 mm.
Adult bedbugs are reddish brown, flattened, oval, and wingless, with microscopic hairs that give them a banded appearance.
A common misconception is that they are not visible to the naked eye, but adults grow to about 5 mm (three-sixteenths of an inch) in length and do not move quickly enough to escape the notice of an attentive observer.
Bedbugs are generally active only at night, and their peak attack period is usually roughly an hour before local dawn. They will sometimes, however, attempt to feed at other times of day if food is near. Attracted by warmth and the presence of carbon dioxide, the bug pierces the skin of its host with two hollow tubes. With one tube, it injects its saliva, which contains anticoagulants and anesthetics. With the other, it withdraws the blood of its host. (Thanks to the anesthetics, when the host actually feels a ‘bite’ sensation, that is skin’s reaction to the bite, not the bite itself.)
After feeding — a typical meal lasts about 5 minutes — the bug returns to its lair. Although bedbugs can live for up to 18 months without a food source, they will not voluntarily abstain from food for that entire time; if a food source is available, they will usually seek food on a weekly basis.
Many individuals erroneously associate bedbugs with filthy conditions. In truth, as mentioned above, they are attracted by exhaled carbon dioxide and not dirt, and feed off blood, not waste. They are found as often in immaculately clean locations as in poorly kept conditions.
While bedbugs have been known to harbor pathogens in their bodies, including plague and hepatitis B, they have not been linked to the transmission of any disease and are not regarded as a medical threat.
Female bedbugs can lay up to five eggs in a day and 500 during a lifetime. The eggs are almost invisible to the naked eye and are a milky white tone in color.
A few bedbug species make use of a mating plug, which a male inserts post-copulation. Effectively the male seals her vaginal opening upon withdrawal. This has a distinct evolutionary advantage as it prevents other males from mating with her. Some bedbug species thus employ stabbing rape, where the male impales the female via her abdomen and thus circumvents the mating plug.
In Xylocaris maculipennis, the male will at times impale and inseminate other males while they are engaged in the process of copulation. This allows the rapist’s genes to enter the bloodstream to be carried to females by the victim. In this way, the rapist conceives by proxy. In A Natural History of Sex, Adrian Forsyth writes, “The sperm of the rapist enters the vas deferens of his male victim and is used by the victim during copulation.”
Bed Bug Infestations
Method of initial infestation
With the widespread use of DDT in the 1940s and ’50s, bedbugs all but disappeared from North America in the mid-twentieth century. Infestations remained common in many other parts of the world, however, and in recent years have begun to rebound in North America.  The insects have become endemic in the Boston suburbs of Allston and Brighton, Massachussetts, where in 2004 renters were offered subsidies to replace infested mattresses. 
Another reason for their increase is that pest control services more often nowadays use gel-based pesticides, instead of aerosols, when attacking insect infestations. While aerosol sprays meant to kill other insects can result in a collateral insecticidal effect on bedbugs, gel-based insecticides are not known to have any effect on bedbugs and thus leave them unaffected.
There are several means by which dwellings can become infested with bedbugs. People can often acquire bedbugs at hotels, motels, and bed-and-breakfasts, thanks to increased domestic and international tourism, and bring them back to their primary domiciles in their luggage. They also can pick them up by adding infested furniture to their household either via purchase or “dumpster diving”. If someone is in a place that is severely infested, bedbugs may actually jump onto and be carried by people’s clothing, although this is atypical behavior — except in the case of severe infestations, bedbugs are not usually carried from place to place by people on clothing they are currently wearing. Finally, it is extremely common for bedbugs to travel in multi-unit dwellings (such as condominiums and apartment buildings) from unit to unit, after having been originally brought into the building by one of the above techniques.
Common location of infestations
Due to the thin, flat nature of their bodies, bedbugs are able to hide in cracks and crevices. They often will congregate in locations within a dwelling which are shielded from sunlight, including but not limited to the seams and inside cushioning of mattresses and chairs, supporting frames for beds, and baseboards. Although bedbugs can hide individually, they are social creatures and more often will congregate in groups.
Size of infestations
Some pest control professionals have deemed light infestations to be anything below 200 bedbugs in a residence; a medium infestation can be in the range of 200–300 bedbugs in a residence; and severe infestations can be as bad as 2,000–3,000 bedbugs in a single residence.
Detection of infestations
Bedbugs can be detected often by looking for black tracks on bedding, which are the bedbugs’ fecal stains. (The stains show up best on white- or light-colored bedding, and may be more difficult to see on darker bedding.) When a bedbug is killed by crushing, the result is a blood smear on whatever surface they were squished against (mattress or thumb), assuming that they had already fed. Crushing them also will produce a unique sickly sweet scent, which can also be detected when a dwelling is severely infested.
They can also be detected by their unique bite pattern of a linear group of three, sometimes macabrely referred to as a “breakfast, lunch, dinner” pattern. (Bedbug bites are often in this pattern, but can also occur singly.) The effect of these bites on humans varies from person to person, but oft produce welts and swelling that are more itchy and longer-lasting than mosquito bites. Some people, however, have little or no reaction.
If an individual finds themselves awake in the middle of the night, a flashlight can be run up and down a mattress or bedding to attempt to locate active bugs. This technique is suggested because the physical vibrations of getting up from the mattress and turning on a room light may give bedbugs sufficient time to retreat to hiding places, making detection more difficult.
Observant watchers could also probably see bedbugs rarely throughout the day, since they move slowly, but yet are still very hard to see.
Living with infestation
Prior to treatment, if it is necessary to live for any prolonged period of time with bedbugs, and if the mattress, boxspring and frame is known to be bug-free, one can isolate the mattress from bedbugs by applying Vaseline or double-sided sticky tape around the circumference of the bedframe legs, or by placing the legs in glass jars. The purpose of these actions (Vaseline, sticky tape, glass jars) is to make it impossible for bedbugs to climb the legs of the bed in order to get to the sleeper. If you feel your bed may already be infested, create a “safe zone” by putting a layer of 2 millimeter plastic over the mattress and wrap the edges in carpet tape (double-stick tape). Make sure all bedding (including pillows) are bug-free by putting them in a clothes drier with temperatures above 120 degrees Fahrenheit for an hour. Lastly, try and keep all bedding from going over the edges of your mattress.
Removal of infestations
Due to their absence from North America for several decades, not all exterminators are familiar with extermination techniques for bedbugs. Those who are unfamiliar with bedbug extermination techniques may attempt to use ineffectual techniques, such as fumigation. Care must thus be taken when selecting an exterminator, in order to select a professional that knows how to conduct proper bedbug removal.
Necessary Number of Treatments
An informal survey of pest control professionals conducted by a pest control professor at the University of Massachusetts stated that 68% of all bedbug infestations require three or more treatments, 26% require two treatments, and 6% require just one. However, this survey does not seem to taken into account the size of the infestation, the size of the venue being treated, the extensiveness of that venue’s preparation for the treatment (thus enabling or inhibiting coverage of the poisons), the skill of the exterminator, whether popular nesting places have been disposed of, and the cause behind the original infestation; its veracity must thus be questioned.
Preparation of Dwelling for Treatment
Most exterminators will require that the dwelling be prepared in certain ways prior to their treatment. All furniture and appliances in the dwelling usually need to be pulled away from the baseboards, and it is commonly asked that all furniture containing cracks or crevices (such as bookshelves and desks) be emptied and left open for the exterminator to spray. Items that are enclosed in things that securely snap shut, creating nearly airtight seals, usually remain protected from bedbug infestation and need not be emptied.
All objects able to be laundered (not only clothing but rugs, stuffed animals, and so on) need to either be laundered or dry-cleaned. Laundered objects should be encased in securely tied garbage bags prior to their emptying into the laundry machine. Regardless of the fabric’s color, laundered objects should be washed in hot water and dried using high heat. Once clean, these objects should be separated from a still-infested dwelling again by the use of securely tied garbage bags. Ideally, if manpower permits, laundry should be done all at once just prior to or just after treatment, to minimize the chance of the laundered objects being reinfested.
Baseboards should be vacuumed — not swept — prior to the exterminator’s arrival, and the filter should be immediately removed from the vacuum and taken to an outside garbage can.
People dealing with bedbug infestations have had mixed success with retaining mattresses, boxsprings, futons, pillows, and other infested bedding. Although some insecticides specifically exist for treatment of bedding, individuals may wish to strongly consider throwing away and replacing existing bedding, especially if said material is already aged or in poor condition. Note that when moving possibly infested items through a multi-unit dwelling towards a dumpster, it is best to enclose said items in garbage bags or protective covers to prevent bedbugs from jumping off of (or being knocked off of) the object(s) while in transit. Bedbugs knocked off in such a fashion could then proceed to infest other units within the multi-unit dwelling. (It may be wise to place a sign that warns of infestation on thrown-away furniture, to prevent it from being taken by others prior to its pick-up by the local waste removal service.)
Often, exterminators will spray a “contact kill” spray on bedbugs seen in the apartment (such as a mixture of cyfluthrin, pyrethrins, and piperonyl butoxide), and then spray lambda-cyhalothrin on baseboards and other areas of the apartment. Lambda-cyhalothrin acts as a “slow kill” barrier which kills bedbugs after they cross it, and is usually microencapsulated, making it safe to pets and humans after it dries. Often, deltamethrin is also injected into various cracks and crevices of the apartment. The lambda-cyhalothrin and the deltamethrin are at their strongest for the first two weeks following their application, but in total usually last for 60 days.
Bedbugs can often be seen alive for up to two weeks following treatment of a dwelling, although they should not be seen in great number (e.g., only one or two).