Bed bugs feed on blood, principally that of humans, by piercing the skin with their elongated beaks. Although they inflict misery on their victims, it has never been proven that bed bugs 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, crinkly 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 the adults. As they grow, they molt (shed their skins). After each molt they are pale in color and then become 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 begin to feed on blood immediately. Bed bugs reach maturity after five molts. There may be three or more generations each year. Environmental factors and the availability of food will cause considerable variation in the development rate of all stages of growth. Bed bugs may live for several weeks to several months without feeding, depending upon the temperature. Bed bugs feed mostly at night by piercing the skin of people while they sleep. However, if they are very hungry and if the light is dim, they will feed during the day. When bed bugs bite, they inject a fluid into a person’s skin that enables 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 bugs rest. 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 to be found only 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.