Bed bugs feed on blood, principally that of humans, by piercing the skin with their elongated beaks. Although they inflict misery on their victims, bed bugs have never been proven to carry disease-causing pathogens in the United States. Bed bugs are spread chiefly by the clothing and baggage of travelers, secondhand beds, bedding, furniture, and laundry.
A mature bed bug is a dark brown, wingless insect. Its size and color depend on the amount of blood that the body contains. An unfed bed bug is between 1/4 and 3/8 inch long. The upper surface of the body has a flimsy, wrinkled appearance. When engorged with blood, the body becomes elongated and swollen, and the color changes from brown to dull red. Bed bug eggs are white and about 1/32 inch long. Newly hatched bugs are translucent and nearly colorless but similar in shape to adults. As they grow, they molt (shed their skins). After each molt, they are pale and brownish as the exoskeleton hardens.
Under favorable temperatures (above 70 degrees F) and with regular feeding, a female bed bug will lay about 200 eggs during her lifetime at a rate of three or four per day. Eggs are coated with a sticky substance that allows them to adhere to objects on which they are deposited. The eggs hatch in 6 to 17 days, and the nymphs find a host and feed on blood immediately. Bed bugs reach maturity after five molts. There may be three or more generations each year. Environmental factors and food availability will cause considerable variation in the development rate of all stages of growth. Bed bugs may live for several weeks to months without feeding, depending on the temperature. Bed bugs feed primarily at night by piercing people’s skin while they sleep. However, if they are starving and if the light is dim, they will provide during the day. When bed bugs bite, they inject fluid into a person’s skin, enabling the insect to withdraw blood. Often the fluid causes the skin to become irritated, inflamed, and itchy. The bite produces elongated, spindle-shaped welts. This elongated spindle shape distinguishes the welts from those from mosquito or flea bites. If its feeding is undisturbed, a full-grown bed bug becomes engorged with blood in 3 to 5 minutes. It then crawls to its hiding place, where it remains for several days, digesting its meal. When hungry, the bug emerges from hiding and seeks another host for a blood meal.
Bed bug hiding places are evident by black or brown spots of dried excrement on surfaces where the rest of the bug is. Eggs, egg shells, and cast skins also may be seen near these places. At the beginning of an infestation in a room, bed bugs are likely only found in the tufts, seams, and folds of mattresses and covers. Later they spread to crevices in the bedsteads. If allowed to multiply, they establish themselves behind baseboards, window and door casings, pictures and picture moldings, and in furniture, loosened wallpaper, cracks in plaster, and partitions.