After being all but invisible for half a century,

bed bugs are back with a vengeance in the US.

Most Americans have never dealt with a bed bug. Until recently, they were a rarity even among most pest control professionals. Although bed bug infestations were common in the US prior to WWII, improvements in hygiene and the introduction of more effective pesticides (DDT) in the '40s and '50s made bed bugs an insignificant pest. They were still common in other regions of the world, however, and in recent years bed bugs have made a dramatic comeback in the US. The biggest contributors for this resurgence are greater rates of immigration, more international travel and the expansion of global trade. Add to this the introduction of new pest control practices that leave bed bugs unharmed as well as the removal of many effective pesticides and you have the makings of an outbreak.

Bed bugs are about 1/8-inch long and reddish-brown with oval, flattened bodies.

Four-segmented antennae are attached to the head between the prominent compound eyes. The proboscis is located beneath the head and passes back between the front legs. They feed solely on the blood of animals. They first got a taste for human blood when cave-dwelling humans lived beneath bug-infested bat roosts. Bed bugs do not fly but can move swiftly over walls, floors and ceilings. Females attach their eggs in secluded areas. The eggs are whitish and very hard to see with the naked eye. Under ideal conditions, eggs hatch in about seven days. Newly hatched nymphs shed their skin approximately five times before reaching maturity. A blood meal is required between each successive molt. Bed bugs complete development in about one month, producing three or four generations per year. Bed bugs are very resilient and resourceful, they can survive for months without feeding and in the absence of humans, they will bite other warm-blooded animals, including pets.

Bed bugs are nocturnal. During the daytime, they hide in cracks close to where humans sleep. The prefer tiny crevices in mattresses, box springs, bedframes and headboards. In these hiding spots you will find fecal stains, eggs, molted skins, blood spots and in heavy infestations, a musty odor. As the population grows, they will spread to other cracks and crevices throughout the room, adjacent rooms and other apartments. Bed bugs are attracted to humans by body heat and emissions of carbon dioxide. As they bite, they inject an anesthetic which allows them to feed undetected. They typically require a 5 to 10-minute blood meal in order to completely engorge themselves. The saliva that is injected in the puncture results in circular, red, itchy welts. Although more than 25 infectious agents have been associated with bed bugs, they are not considered vectors of disease since these pathogens are not transmitted.