Bed bugs (family Cimicidae) have been associated with humans for a long time. They are considered unappealing by most people and are wrongfully associated with poor housekeeping. There are several species of bed bugs that people may encounter in Minnesota. The two most common are the bat bug (Cimex adjunctus) and the human bed bug (Cimex lectularius). These two insects are virtually indistinguishable with the naked eye. Their habits, and consequently their control, vary, however, making identification important.
Appearance of Bed Bug Species
The mature bed bug is a flattened, brown, wingless insect approximately ¼ to 3/8 inch long. After it has taken a blood meal, the color changes from brown to purplish-red. The size and shape also change, making it appear like a different insect. Young bed bugs are nearly colorless and smaller but resemble the adult in general shape.
Feeding Habits
Bed bugs feed mostly at night while people are sleeping. Occasionally they feed during the day, particularly if the light is dim.
When bed bugs bite, they inject saliva under the skin to help them feed on the blood. The bite itself is usually painless, but the saliva may cause itching, which may become intense in some individuals. The site of the bite may swell, leaving a lump. Generally the center of this area does not turn red. Bed bugs are not known to transmit diseases to humans.
Where They Hide
Bed bugs can infest anywhere where humans live but are most common in bedrooms or other sleeping areas. They do not normally travel far so they need to live near their food source(s). Bed bugs are active at night and hide in cracks and crevices during the day. Some of these hiding places may include: in tufts, seams, and folds of mattresses and bed covers; in boxsprings; in cracked and hollow bedframes; in upholstery of other furniture; behind baseboards, peeling wallpaper, pictures; and in light fixtures. Anywhere that offers darkness and protection can be a potential bed bug hiding place. Determining their hiding places is a sometimes difficult, though essential, step in successful bed bug control.
Look for black and brown spots of dried excrement (composed primarily of blood); this can help pinpoint bed bug hiding areas. Eggs and cast skins are also signs of bed bug infestation. Sometimes a distinctive odor may be detected.
Bat Bugs
The most commonly encountered bed bug is the bat bug. As the name suggests, these insects are associated with bats; a bat bug infestation indicates bats are also living in the home. Bat bugs prefer bats as a host but will feed on human blood in their absence.
Bat bugs differ from bed bugs by having longer hairs on the prothorax and having wing pads that are broadly joined on the inner margin; magnification is usually needed to see these details. If there is any doubt as to the insect's identification, send a specimen to a specialist for verification.
Although bat bugs are more commonly encountered in Minnesota, they have not been as thoroughly studied as bed bugs. However, it is expected the habits of bat bugs is very similar to bed bugs.
Human Bed Bugs
Mature bed bug
With the advent of more effective insecticides, human bed bugs have been easier to control and have become relatively uncommon pests.
Human bed bugs may be encountered in homes, motels, hostels, movie theaters, transportation depots, and rest rooms. They may be accidentally moved with clothes, suitcases, furniture, and other personal items. Human bed bugs may also be transported in second-hand or rental furniture.
Life Cycle
The adult female human bed bug lays one to five eggs per day. She may lay a total of 200 eggs when well fed and temperatures are higher than 70° F. The eggs are sticky when freshly laid so they adhere to the object on which they are placed. Eggs hatch in six to 17 days.
Newly hatched bugs feed immediately when food is available. They molt five times (i.e., they shed their outer skin or exoskeleton in order to grow) before reaching maturity, feeding between each molt. There may be three or more generations per year. All ages are found in a reproducing population.
The young bugs may live for several weeks without feeding during warm weather and for several months during cool weather. A single bug will live for 10 months when it can obtain food. Under some conditions, it may live a year or longer without food.
An adult human bed bug becomes engorged with blood in about 10 to 15 minutes, a young bed bug in as little as three to five minutes. It then returns to its hiding place until the blood meal is digested. The bed bug will take repeated feedings.
Less Frequently Encountered Bed Bugs
Other species of bed bugs may be encountered in Minnesota. The chimney swift bug, Cimexopsis nyctalis, and the swallow bug, Oeciacus vicarius, feed primarily on birds. However, they can occasionally be pests in houses when the host bird is associated with the home. Like bat bugs, these other species will also feed on humans in the absence of their normal hosts.
Nonchemical Control
Wash infested sheets and bedding in hot water. Infested furniture can be set outside during cold weather to kill all stages of bed bugs. At 0° F, two days is sufficient to kill bed bugs while four to five days is required when the temperature is about 20° F.
Seal cracks and crevices where bed bugs may hide. Repair or remove loose wallpaper. Remove pictures, posters, or other objects that may act as hiding places.
In the case of bat bugs, exclude bats from roosting in the building (for more information see Bats, Minnesota Extension Service Fact Sheet FS-1141). If a problem arises with one of the bird-related bed bugs, the nest can be removed as long as the birds are in the process of nest-building. Since these birds are protected, no action can be taken directly against them that may cause them harm. If the problem is encountered other than during the birds' nest-building period, contact the United States Department of Agriculture, Animal & Plant Health Inspection Service—Animal Damage Control.
Chemical Control
It is unlikely that nonchemical methods alone will eradicate bed bugs. If insecticides are needed to supplement nonchemical means, apply them to all cracks, crevices, and other areas where bed bugs may hide. To treat a bed, spray the spring, slats, and frame thoroughly. Spray the mattress, including the tufts and folds; allow the mattress to dry before remaking and occupying it. Spray upholstered furniture. When treating walls and baseboards, be sure to spray cracks and crevices. Spray behind loose wallpaper or wallboards as these often provide hiding places.
Choose one of the following insecticides: chlorpyrifos, permethrin, propoxur (e.g. Baygon) [may be listed as o isopropoxyphenyl methylcarbamate], cyfluthrin, fenvalerate [may be listed as cyano (3-phenoxyphenyl) methyl 4-chloro alpha-(1-methyl-ethyl) benzeneacetate, tetramethrin, resmethrin [may be listed as (5-benzyl-3-furyl) methyl 2,2-dimethyl-3-(2-methylpropenyl) cyclopropanecarboxylate], or d-trans allethrin. These insecticides are purchased in ready-to-use aerosol or liquid forms from hardware stores, retail variety stores and similar places.
CAUTION: Read all label directions carefully before buying insecticides and again before applying them to ensure their proper use. Do not overspray, especially in and around beds.
Commercial pest control companies are also available to control bed bugs, if desired. Their experience and larger selection of insecticides may increase your chances of successfully eradicating a bed bug population.