Dr. Stephen A. Kells, Assistant Professor
Jeff Hahn, Extension Professor
Department Entomology
University of Minnesota
Bed bugs, Cimex lectularius, have resurged to quickly become a very important pest of the 21st century, as they invade numerous urban areas. Our society has had a 30+ year "vacation" from this pest, when bed bugs were almost completely removed from North America as a result of mass treatments with older types of insecticides (DDT, Chlordane, Lindane). Recently though, bed bugs have found ample opportunity to increase in numbers and spread through society. Their success is a result of a combination of factors: increased travel of people; improved treatment methods that specifically target other insect pests (and thus not impact bed bugs); and the lack of public awareness. In addition to homes and hotels, bed bugs are also being found in schools, retail facilities, office buildings, libraries, and other public areas.
Why are they important?
Bed bugs are parasites that feed on the blood of people, using these blood meals to grow and reproduce. They do not distinguish between dirty or clean homes and all people are vulnerable to infestations in their homes. Bed bugs are also capable of feeding on animals, including dogs, cats, and other pets.
They live close to areas where people typically sleep, rest, or sit for long periods. Hungry bugs will move out from their hiding places, in search of exposed skin. Typically, the head and neck are bitten, but bed bugs will also bite bare arms, hands, and legs. When searching for a place to feed, these bugs can move very quickly. Once an appropriate site is found, they feed for 2-5 minutes until full, and then move quickly away from the person and into a hiding place.
In addition to bed bugs moving towards a person when they are least likely to notice the insects, the result of their bites may also go unnoticed, or can be mistaken for the bites of other pests. All people are not equally sensitive to bed bug bites, so while some victims break out in rashes from the bites, other people may not display symptoms. When a reaction does occur, the results of feeding can be mild (a simple red spot) to severe (rash or even hives). The reactions caused by feeding might be mistaken for other problems. Fleas, mosquitoes and other biting insects, sensitization to detergents and soaps, and irritants (e.g., poison ivy) are some of the conditions victims of bed bugs thought they were dealing with.
Bed bugs are not known to transmit disease to people. They have been discovered to harbor 28 different human pathogens, but fortunately, the transmission of these diseases to people has not been demonstrated.
What do they look like?
Adult bed bugs are oval, flattened, brown, and wingless insects approximately 1/4" to 3/8" long (5-9 mm). They are similar in appearance to a wood tick. After the bug has taken a blood meal, its color will change from brown to purplish-red. Also after feeding, it is larger and more cigar-shaped making it appear like a different insect. Young bed bugs are much smaller, 1/16" (1.6 mm) when they first hatch, and nearly colorless except after feeding, but resemble the adult in general shape. You may also find cast skins, which are empty shells of bugs as they grow from one stage to the next. After a blood meal, bed bugs deposit fecal spots (composed of digested blood) in areas adjacent to the feeding site or back at their hiding places.
What is their life cycle?
Bed bugs are active at night and generally hide during the day. After mating, females lay white, oval eggs (1/16-inch long) into cracks and crevices. An individual bed bug can lay 200-250 eggs in her lifetime. The eggs hatch in about 6-10 days and the newly emerged bed bug nymphs seek a blood meal. Immature nymphs molt five times (i.e., they shed their outer exoskeleton in order to grow) before reaching adulthood. They need to feed at least once before each molt, although they could feed as often as once a day. There may be three or more generations per year. All ages are found in a reproducing population. Immature bed bugs may live for several months without feeding while adults may survive as long as one year without a meal. Under normal circumstances, adult bed bugs will live for about ten to eleven months.