Common Bed Bug

Cimex lectularius — the common bed bug — is one of the oldest documented human-associated insects, with evidence of bed-bug presence in human shelters dating back at least 3,500 years to ancient Egypt. The species is a strict obligate hematophage (blood feeder) on warm-blooded hosts, with humans as the preferred meal. Adults are flat, oval, reddish-brown, and roughly 4–5 mm long — the size of an apple seed. Bed bugs feed for 5–10 minutes once every 3–7 days, secreting an anticoagulant and a mild anesthetic that lets the bite go unnoticed. They locate hosts by detecting body heat and CO₂ from up to 1.5 m. Reproduction is via traumatic insemination — the male's sharpened genital structure pierces directly through the female's abdomen wall, injecting sperm into a specialized organ. Females survive thousands of these matings over their lifespan, but the energetic cost is significant. Bed bugs nearly disappeared from North America and Europe by the 1950s due to widespread DDT and chlordane use; the species rebounded dramatically in the early 2000s with international travel and pyrethroid resistance. They have evolved at least 14 distinct mechanisms of insecticide resistance and can survive a full year between blood meals at low temperatures.