The insect family Cimicidae contains species commonly called bed bugs, bat bugs, and swallow bugs. Bed bugs are found in temperate and tropical regions worldwide. The 91 species in this family are wingless, obligate hematophagous ectoparasites that feed on bats, birds, and mammals. The word Cimex is derived from the Roman designation for bug and lectularius from the Latin name for couch or bed. Only 2 species, Cimex lectularius and Cimex hemipterus, readily feed on humans but others may rarely do so as well.

Adult bed bugs are oval shaped, flat, and approximately 1/4 inches long. They resemble unfed ticks or small cockroaches and are easily visible, even to the untrained eye. Adults are reddish brown (chestnut) in color, whereas immature ones, Nymphs, are much smaller and may be light yellow to almost clear. They have a pyramid-shaped head with prominent compound eyes, slender antennae, and a long proboscis tucked underneath the head and thorax. After a blood meal, the bugs may increase in length by 30% to 50% and in weight by 150% to 200%.

By nature, bed bugs are stow-a-ways. They enter homes or apartments by hiding out in the cracks and crevices of luggage, furniture, clothing, pillows, boxes and other objects when they are moved between apartments, homes and hotels. Bed bugs hide during the day and typically feed at night. Since bed bugs feed on blood, their presence has little to do with the cleanliness of the home, although clutter can provide hiding spaces for bed bugs and make them difficult to treat. Bed bugs can survive for up to 16 months without feeding, so they may be present in vacant, clean homes when new tenants unpack. Once bed bugs are established, they rapidly reproduce and spread from room to room.

Bed bugs can be very difficult to control. Many insecticides are not effective at killing the eggs, so a repeat treatment is often necessary to kill the juveniles after they hatch. Even worse, some populations of bed bugs have developed resistance to common insecticides, making some sprays ineffective. Alternative methods include heat and steam treatments, structural fumigation and cold treatments.