page_title: Hemiptera
section_title: As human parasites and disease vectors
hierarchical_section_title: Hemiptera / Interaction with humans / As human parasites and disease vectors
caption_attribution_description: ID#: 9822 This 2006 photograph depicted an oblique-dorsal view of a bed bug nymph (Cimex lectularius) as it was in the process of ingesting a blood meal from the arm of a “voluntary” human host. Bed bugs are not vectors in nature of any known human disease. Although some disease organisms have been recovered from bed bugs under laboratory conditions, none have been shown to be transmitted by bed bugs outside of the laboratory. The common bed bug is found worldwide. Infestations are common in the developing world, occurring in settings of unsanitary living conditions and severe crowding. In North America and Western Europe, bed bug infestations became rare during the second half of the 20th century and have been viewed as a condition that occurs in travelers returning from developing countries. However, anecdotal reports suggest that bed bugs are increasingly common in the United States, Canada, and the United Kingdom. C. lectularius inject saliva into the blood stream of their host to thin the blood, and to prevent coagulation. It is this saliva that causes the intense itching and welts. The delay in the onset of itching gives the feeding bed bug time to escape into cracks and crevices. In some cases, the itchy bites can develop into painful welts that last several days. Bed bug bites are difficult to diagnose due to the variability in bite response between people, and due to the change in skin reaction for the same person over time. It is best to collect and identify bed bugs to confirm bites. Bed bugs are responsible for loss of sleep, discomfort, disfiguring from numerous bites and occasionally bites may become infected.
context_page_description: The Hemiptera or true bugs are an order of insects comprising some 50,000 to 80,000 species of groups such as the cicadas, aphids, planthoppers, leafhoppers, and shield bugs. They range in size from 1 mm to around 15 cm, and share a common arrangement of sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera. Many insects commonly known as "bugs", especially in American English, belong to other orders; for example, the lovebug is a fly and the May bug and ladybug are beetles.
  Most hemipterans feed on plants, using their sucking and piercing mouthparts to extract plant sap. Some are hematophagous, while others are predators that feed on other insects or small invertebrates. They live in a wide variety of habitats, generally terrestrial, though some species are adapted to life in or on the surface of fresh water. Hemipterans are hemimetabolous, with young nymphs that somewhat resemble adults. Many aphids are capable of parthenogenesis, producing young from unfertilised eggs; this helps them to reproduce extremely rapidly in favourable conditions.
  Humans have interacted with the Hemiptera for millennia.
context_section_description: Chagas disease is a modern-day tropical disease caused by Trypanosoma cruzi and transmitted by kissing bugs, so-called because they suck human blood from around the lips while a person sleeps.
  The bed bug, Cimex lectularius, is an external parasite of humans. It lives in bedding and is mainly active at night, feeding on human blood, generally without being noticed. Bed bugs mate by traumatic insemination; the male pierces the female's abdomen and injects his sperm into a secondary genital structure, the spermalege. The sperm travel in the female's blood (haemolymph) to sperm storage structures (seminal conceptacles); they are released from there to fertilise her eggs inside her ovaries.
caption: Bed bug nymph, Cimex lectularius, engorged with human blood
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