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Bed bugs are blood-sucking insects in the family Cimicidae. Both nymphs and adults feed on humans mostly at night, a time when it is difficult to detect their stealthy habits.
Cimex lectularius is a cosmopolitan, or widely distributed, species, most frequently found in the northern temperate climates of North America, Europe, and Central Asia. It occurs more sporadically in southern temperate regions. In tropical regions, C. hemipterus is the dominant species, but this species does not occur in California. The most common species found in California is C. lectularius.
The growth and development of C. lectularius is optimal when it feeds on humans; however this insect also feeds on other species of mammals and birds found near the home including chickens, mice, rats, and rabbits.
Until recently, bed bug infestations were thought to be associated primarily with crowded and dilapidated housing. However, such infestations have undergone a resurgence and can be found even in the finest hotel and living accommodations. The reasons for the resurgence are not totally understood but appear to involve increased human travel, ease of movement of infested luggage and items, and changes in the pesticides available to control this pest.
IDENTIFICATION AND LIFE CYCLE
Adult bed bugs are oval, wingless, about 1/5 inch long, and rusty red or mahogany. Their bodies are flattened, they have well-developed antennae, their compound eyes are small, and the area behind the head (the prothorax) expands forward on either side of the head. The immature's appear identical to the adults except for their smaller size, thinner outer skeleton (cuticle), and lighter, yellowish-white color.
Bed bugs are readily distinguished from another common blood-sucking species, conenose bugs, by their smaller size, more rounded shape, and lack of wings as adults. Conenose, or kissing, bugs may be up to 3/4 inch long.
Female bed bugs lay 200 to 500 tiny, white eggs in batches of 10 to 50 on rough surfaces such as wood or paper. Glue-like material covers the eggs, which hatch in about 10 days. After hatching occurs, the eggshells frequently remain stuck in place.
There are five progressively larger nymphal stages, each requiring a single blood meal before molting to the next stage. The entire life cycle from egg to adult requires anywhere from 5 weeks to 4 months, depending on temperature and availability of food (blood). When temperatures are in the range of 70° to 82°F, development occurs most rapidly.
Nymphs and adults generally feed at night and hide in crevices during the day. Common hiding places include seams in mattresses and box springs, cracks in bed frames, under loose wallpaper, behind picture frames, and inside furniture and upholstery. Occasionally people pick up bed bugs in theaters or on buses and trains. They also can bring them into their home on clothing, bedding, luggage, or firewood.
Bed bugs can go without feeding for 80 to 140 days. Older stages of nymphs can survive longer without feeding than younger ones, and adults have survived without food for as long as 550 days. A bed bug can take six times its weight in blood, and feeding can take 3 to 10 minutes. Adults live about 10 months, and there can be up to 3 to 4 generations of bed bugs per year.
DAMAGE
Bed bugs feed on humans, usually at night when they are asleep. They feed by piercing the skin with their elongated mouthparts, which consist of two stylets that normally fold under their body when at rest but fully extend during blood-meal feeding. One stylet has a groove that carries saliva into the wound, while the other has a groove through which body fluids from the host are taken in.
A single feeding may take up to 10 minutes, and feels like a pin prick, but because feeding usually occurs at night when people are asleep they are not aware they have been bitten until afterwards. However, saliva injected during the feeding can later produce large swellings on the skin that itch and may become irritated and infected when scratched. Swelling may not develop until a day or more after feeding, and some people do not show symptoms. Bed bugs currently are not considered to be disease carriers.
Distinguishing bed bug bites from the bites of other arthropods such as mosquitoes, fleas, and spiders is difficult. People often confuse itching bed bug welts for mosquito bites. The only way you really can confirm bed bugs are the cause is to find the bugs in your bed or bedroom. Often people are bitten when traveling, making diagnosis even more difficult.
In addition to the direct injury to humans, bed bugs have stink glands that leave odors. They also leave unsightly fecal spots on bed sheets and around their hiding places. These spots are darkish red in color, roughly round, and can be very small.
