A bedbug is a small nocturnal insect of the family Cimicidae that lives by hematophagy, or by feeding on the blood of humans and other warm-blooded hosts. 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 (as well as 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 Cimex pipistrella primarily infest bats, while Haematosiphon inodora, a species of North America, primarily infests poultry. Adult bedbugs are a 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. Adults grow to 4 to 5 mm (one-eighth to three-sixteenths of an inch) in length and do not move quickly enough to escape the notice of an attentive observer. Newly hatched nymphs are translucent, lighter in color and continue to become browner and moult as they reach maturity. When it comes to size, they are often compared to lentils or appleseeds.
Bedbugs are generally active only at dawn, with a peak attack period about an hour before dawn, though given the opportunity, they may attempt to feed at other times. 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, while with the other it withdraws the blood of its host. After feeding for about five minutes, the bug returns to its hiding place. The bites cannot usually be felt until some minutes or hours later, as a dermatological reaction to the injected agents.
Although bedbugs can live for a year or as much as 18 months without feeding, they typically seek blood every five to ten days. Bedbugs that go dormant for lack of food often live longer than a year, well-fed specimens typically live six to nine months. Low infestations may be difficult to detect, and it is not unusual for the victim not to even realize they have bedbugs early on. Patterns of bites in a row or a cluster are typical as they may be disturbed while feeding. Bites may be found in a variety of places on the body.
Bedbugs may be erroneously associated with filth in the mistaken notion that this attracts them. However, severe infestations are often associated with poor housekeeping and clutter. Bedbugs are attracted by exhaled carbon dioxide and body heat, not by dirt, and they feed on blood, not waste. In short, the cleanliness of their environments has effect on the control of bedbugs but, unlike cockroaches, does not have a direct effect on bedbugs as they feed on their hosts and not on waste. Good housekeeping in association with proper preparation and mechanical removal by vacuuming will certainly assist in control.
All bedbugs mate via a process termed traumatic insemination. Instead of inserting their genitalia into the female's reproductive tract as is typical in copulation, males instead pierce females with hypodermic genitalia and ejaculate into the body cavity. This form of mating is thought to have evolved as a way for males to overcome female mating resistance. Traumatic insemination imposes a cost on females in terms of physical damage and increased risk of infection. To reduce these costs females have evolved internal and external "paragenital" structures collectively known as the “spermalege”. Within the True Bugs (Heteroptera) traumatic insemination occurs in the Prostemmatinae (Nabidae) and the Cimicoidea (Anthocoridae, Plokiophilidae, Lyctocoridae, Polyctenidae and Cimicidae), and has recently been discovered in the plant bug genus Coridromius (Miridae).
Remarkably, in the genus Afrocimex both males and females possess functional external paragenitalia, and males have been found with copulatory scars and the ejaculate of other males in their haemolymph. There is a widespread misbelief that males inseminated by other males will in turn pass the sperm of both themselves and their assailants onto females with whom they mate. While it is true that males are known to mate with and inject sperm into other males, there is however no evidence to suggest that this sperm ever fertilizes females inseminated by the victims of such acts.
Female bedbugs can lay up to five eggs in a day and 500 during a lifetime. The eggs are visible to the naked eye measuring 1 mm in length (approx. two grains of salt) and are a milky-white tone. The eggs hatch in one to two weeks. The hatchlings begin feeding immediately. They pass through five molting stages before they reach maturity. They must feed once during each of these stages.
At room temperature, it takes about five weeks for a bedbug to pass from hatching to maturity. They become reproductively active only at maturity.
In most observed cases a small, hard, swollen, white welt may develop at the site of each bedbug bite. This may be accompanied by severe itching that lasts for several hours to days. Welts do not have a red spot in the center such as is characteristic of flea bites. Some individuals respond to bed bug infestations with anxiety, stress, and insomnia. Individuals may also get skin infections and scars from scratching the bedbug bites.
Most patients that are placed on systemic corticosteroids to treat the itching and burning often associated with bed bug bites find that the lesions are poorly responsive to this method of treatment. Antihistamines have been found to reduce itching in some cases, but they do not affect the appearance and duration of the lesions. Topical corticosteroids, such as hydrocortisone, have been reported to expediently resolve the lesions and decrease the associated itching.
Bed bugs seem to possess all of the necessary prerequisites for being capable of passing diseases from one host to another, but there have been no known cases of bed bugs passing disease from host to host. There are at least twenty-seven known pathogens (some estimates are as high as forty-one) that are capable of living inside a bed bug or on its mouthparts. Extensive testing has been done in laboratory settings that also conclude that bed bugs are unlikely to pass disease from one person to another. Therefore bedbugs are less dangerous than some more common insects such as the flea. However, transmission of trypanosomiasis (Chagas disease) or hepatitis B might be possible in appropriate settings.
The salivary fluid injected by bed bugs typically causes the skin to become irritated and inflamed, although individuals can differ in their sensitivity. Anaphylactoid reactions produced by the injection of serum and other nonspecific proteins are observed and there is the possibility that the saliva of the bedbugs may cause anaphylactic shock in a small percentage of people. It is also possible that sustained feeding by bedbugs may lead to anemia. It is also important to watch for and treat any secondary bacterial infection.
Bedbugs travel easily and quickly along pipes and boards, and their bodies are very flat, which allows them to hide in tiny crevices. In the daytime, they tend to stay out of the light, preferring to remain hidden in such places as mattress seams, mattress interiors, bed frames, nearby furniture, carpeting, baseboards, inner walls, tiny wood holes, or bedroom clutter. Bedbugs can be found on their own, but more often congregate in groups. Bedbugs are capable of travelling as far as 100 feet to feed, but usually remain close to the host in bedrooms or on sofas where people may sleep.
There are several means by which dwellings can become infested with bedbugs. People can often acquire bedbugs at hotels, motels, and bed-and-breakfasts, as a result of increased domestic and international tourism, and bring them back to their homes in their luggage. They also can pick them up by inadvertently bringing infested furniture or used clothing to their household. If someone is in a place that is severely infested, bedbugs may actually crawl 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, bedbugs may travel between units in multi-unit dwellings (such as condominiums and apartment buildings), after being originally brought into the building by one of the above routes. This spread between units is dependent in part on the degree of infestation, on the material used to partition units (concrete is a more effective barrier to the spread of the infestation), and whether infested items are dragged through common areas while being disposed of, resulting in the shedding of bedbugs and bedbug eggs while being dragged. In some exceptional cases, the detection of bedbug hiding places can be aided by the use of dogs that have been trained to signal finding the insects by their scent much as dogs are trained to find drugs or explosives. A trained team (dog and handler) can detect and pinpoint a bedbug infestation within minutes. This is a fairly costly service that is not used in the majority of cases, but can be very useful in difficult cases.
The numerical size of a bedbug infestation is to some degree variable, as it is a function of the elapsed time from the initial infestation. With regards to the elapsed time from the initial infestation, even a single female bedbug brought into a home has a potential for reproduction, with its resulting offspring then breeding, resulting in a geometric progression of population expansion if control is not undertaken. Sometimes people are not aware of the insects, and do not notice the bites. The visible bedbug infestation does not represent the infestation as a whole, as there may be infestations elsewhere in a home. However, the insects do have a tendency to stay close to their hosts (hence the name "bed" bugs).
Bedbugs are known for being elusive, transient, and nocturnal, making them difficult to detect.
The presence of bedbugs may be confirmed through identification of the insects collected or by a pattern of bites. Though bites can occur singularly, they often follow a distinctive linear pattern marking the paths of blood vessels running close to the surface of the skin.
A technique for catching bedbugs in the act is to have a light source accessible from bed and to turn it on at about an hour before dawn, which is usually the time when bedbugs are most active. A flashlight is recommended instead of room lights, as the act of getting out of bed will cause any bedbugs present to scatter. If you awaken during the night, leave your lights off but use your flashlight to inspect your mattress. Bedbugs are fairly fast in their movements, about equal to the speed of ants. They may be slowed down if engorged.