Pest Library: Bed Bugs

Bed bugs are parasitic insects of the cimicid family that feed exclusively on blood. Cimex lectularius, the common bed bug, is the best known as it prefers to feed on human blood; other Cimex species specialize in other animals, e.g., bat bugs, such as Cimex pilosellus (Western United States), and Cimex adjunctus (entire Eastern United States). The name bed bug derives from the preferred habitat of Cimex lectularius: warm houses and especially near or inside 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 results from bed bug bites, including skin rashes, psychological effects, and allergic symptoms. Bed bugs are not known to transmit any pathogens as disease vectors. Certain signs and symptoms suggest the presence of bed bugs; finding the adult 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, governmental bans on effective pesticides, and international travel. Because infestation of human habitats has begun to increase, bed bug bites and related conditions have been on the rise as well.

Bed bugs occur around the world. Rates of infestations in developed countries, while decreasing from the 1930s to the 1980s, have increased dramatically since the 1980s.Previously, 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 bed bugs.

The exact causes of this resurgence remain unclear; it is variously ascribed to greater foreign travel, increased immigration from the developing world to the developed world, 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. Declines in household cockroach populations that have resulted from the use of insecticides effective against this major bed bug predator have aided the bed bugs’ resurgence, as have bans on DDT and other potent pesticides. The fall in bed bug populations after the 1930s in the developed world is believed partly due to the use 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 bed bug (C. 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. In November 2016, a media report noted that tropical bed bugs, Cimex hemipterus, which had been extirpated from the state during World War II, were discovered in Brevard County, Florida and are expected to spread in distribution within the United States.