A mature bed bug is an oval-bodied insect, brown to red-brown in color, wingless, and flattened top to bottom. Unfed bugs are 1/4 to 3/8 inch long, and the upper surface of the body has a crinkled appearance. A bug that has recently fed is engorged with blood, dull red in color, and the body is elongated and swollen. Eggs are white, and are about 1/32 inch long. Newly hatched bugs are nearly colorless.
In most parts of the United States the only bed bug of importance to humans is Cimex lectularius. Bed bugs of this species feed on blood, mostly from people, but are also known to feed on bats or other animals including rabbits, rats, guinea pigs, and domestic fowl, especially when the animals are housed in laboratories. The bed bug has a sharp beak that it uses to pierce the skin of the host. It then begins feeding, injecting a fluid that helps in obtaining food. This fluid causes the skin to become swollen and itchy. Bed bugs are nocturnal, feeding at night, often biting people who are asleep. Where infestations are severe one may detect an offensive odor that comes from an oily liquid the bugs emit. Bed bugs can be enticed to bite during the day if light is subdued and they are hungry.
Bed bugs undergo a gradual metamorphosis (change in form) and the young resemble the adult. The young are called nymphs. Under ideal conditions bugs feed regularly when temperatures are above 70° F. Eggs are deposited in batches of from 10 to 50 in crevices of bed frames, floors, walls and similar household sites. When fresh, the eggs are coated with a sticky substance that causes them to adhere to any object on which they are deposited. Eggs are not deposited at temperatures lower than 50° F. Eggs hatch in 6 to 17 days but may take as long as 28 days in cooler temperatures. The nymphs begin to feed as soon as they can locate a host.
They molt 5 times before reaching maturity and the nymphal period lasts about 6 weeks. There may be up to three generations per year in our climate. Bed bugs feed for a period of 3 to 5 minutes, after which they are engorged and drop off the host. They crawl into a hiding place and remain there for several days digesting the meal. When hungry again, they emerge from the hiding place and search for a host. If no food is available, the new nymphs may live for several weeks in warm weather, or several months in cool weather. Older bugs may go for 2 months or longer without food.