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Bed Bugs

HYG-2105
Agriculture and Natural Resources
Date: 
12/06/2020
Benjamin N. Philip, PhD, Program Specialist, Department of Extension 

Bed bugs have been well documented as pests since the 17th century, but evidence of their association with humans is found in archeological sites dating back nearly 3,500 years. They were introduced to the United States by the early colonists. Bed bugs were common in the United States prior to World War II, after which time widespread use of synthetic insecticides such as DDT greatly reduced their numbers. 

Since the 1990s, there has been a resurgence in the prevalence of bed bugs, and they are considered a public health pest by the Environmental Protection Agency (EPA), the Centers for Disease Control and Prevention (CDC), and the United States Department of Agriculture (USDA). International travel and commerce are thought to facilitate the spread of these insect hitchhikers, because eggs, immature, and adult bed bugs are readily transported in luggage, clothing, bedding, and furniture. Furthermore, bed bugs can infest airplanes, ships, trains, and buses. Although bed bugs are frequently found in dwellings with a high rate of occupant turnover, such as hotels, motels, hostels, dormitories, shelters, apartment complexes, tenements, and prisons, they can be found in virtually any building including single-family homes. It should be noted that infestations are not usually a reflection of poor hygiene or bad housekeeping.

Distribution

Bed bugs are fairly cosmopolitan. Cimex lectularius is most frequently found in the northern temperate climates of North America, Europe, and Central Asia, although it occurs sporadically in southern temperate regions. The tropical bed bug, C. hemipterus, is adapted for semitropical to tropical climates and is widespread in the warmer areas of Africa, Asia, and the tropics of North America and South America. In the United States, C. hemipterus occurs in Florida.

Table 1: Common and Scientific Names
Order: Family-Hemiptera: Cimicidae
Common name Scientific name
Bed Bug Cimex lectularius
Tropical Bed Bug Cimex hemipterus


Identification

Adult bed bugs (Figure 1) are brown to reddish-brown, oval-shaped, flattened, and 3/16 to 1/5 inch long (~5 mm). Their flat shape enables them to easily hide in cracks and crevices. Their bodies become more elongate, swollen, and dark red after a blood meal. Bed bugs have a beaklike piercing-sucking mouthpart system. The adults have small, stubby, nonfunctional wing pads. Newly hatched nymphs are nearly colorless, becoming brownish as they mature. Nymphs have the general appearance of adults. Eggs are white and about 1/32 inch (~1 mm) long.

Brown, oval-shaped insect

Figure 1. Adult bed bug. Source: The Ohio State University

Bed bugs superficially resemble a number of closely related hemimetabolous insects (family Cimicidae), such as bat bugs (Cimex adjunctus), chimney swift bugs (Cimexopsis spp.), and swallow bugs (Oeciacus spp.). A microscope is needed to examine the insect for distinguishing characteristics, which often requires the skills of an entomologist.

Life Cycle

Bed bugs are parasites that preferentially feed on humans. Female bed bugs lay from one to 12 eggs per day, and the eggs are deposited on rough surfaces or in cracks and crevices. The eggs are coated with a sticky substance, so they adhere to the substrate. Eggs hatch in six to 17 days, and nymphs can immediately begin to feed. A female bed bug can lay 200-500 eggs in her lifetime. The nymphs require a blood meal in order to molt and reach maturity after five molts (Figure 2). Developmental time (egg to adult) is affected by temperature and takes about 21 days at 86 °F to 120 days at 65 °F. The nymphal period is greatly prolonged when food is scarce. Results from starvation studies with environmental conditions similar to those found in a house demonstrate that late-instar nymphs and adults can live without food for 4-6 months. The adult's lifespan may encompass 12-18 months and three or more generations can occur each year. If humans aren't available as a host, bed bugs instead will feed on warm-blooded animals, including birds, rodents, bats, and pets.

Infestation showing approximately 8 bed bugs, dozens of small, white eggs, and fecal matter

Figure 2. Bed bugs, eggs, and fecal spotting. Source: The Ohio State University

Habits

Bed bugs are fast moving insects that are nocturnal blood feeders. They feed mostly at night when their host is asleep. After using their sharp beak to pierce the skin of a host (Figure 3), they inject a salivary fluid containing an anticoagulant that helps them obtain blood. Nymphs may become engorged with blood within three minutes, whereas a full-grown bed bug usually feeds for 10 to 15 minutes. They then crawl away to a hiding place to digest the meal. 

Bed bugs hide during the day in dark, protected sites. They seem to prefer fabric, wood, and paper surfaces. They usually occur in fairly close proximity to the host, although they can travel far distances and move between rooms in a building. Bed bugs initially can be found in tufts, seams, and folds of mattresses, later spreading to crevices in the bedstead. In heavier infestations, they also may occupy hiding places farther from the bed. They may hide in window and door frames, electrical boxes, floor cracks, baseboards, furniture, and under the tack board of wall-to-wall carpeting. Bed bugs often crawl upward to hide in pictures, wall hangings, drapery pleats, loosened wallpaper, cracks in plaster, and ceiling moldings. 

Two bed bugs, one engorged, feeding on a human host

Figure 3. Bed bugs feeding. Source: The Ohio State University

Injury

The bite is painless. The salivary fluid injected by bed bugs typically causes the skin to become inflamed, although individuals can differ in their sensitivity. A small, hard, swollen, white welt may develop at the site of each bite. This is accompanied by severe itching that lasts for several hours to days. Scratching may cause the welts to become infected. The amount of blood loss due to bed bug feeding typically does not adversely affect the host, however the psychological impacts of anxiety, stress, and insomnia resulting from bites can be severe.

Historically, it was said that rows of three bites on exposed skin are a characteristic sign of bed bugs, however there is not objective evidence this can be diagnostic. 

Although bed bugs are considered by the EPA, the CDC, and the USDA to be a public health pest, it should be noted there is no evidence bed bugs transmit diseases in humans.

Signs of Infestation

A bed bug infestation can be recognized by blood stains from crushed bugs or by rusty (sometimes dark) spots of excrement on sheets and mattresses, bed clothes, and walls. Fecal spots, eggshells, and shed exoskeletons may be found in the vicinity of their hiding places. An offensive, sweet, musty odor from their scent glands that is similar to coriander or cilantro may be detected when bed bug infestations are severe.

Control Measures

A critical first step is to correctly identify the blood-feeding pest, as this determines which management tactics to adopt that take into account specific bug biology and habits. (See Additional Resources below for reference to an identification guide.) Bat bugs closely resemble bed bugs, yet are found near roosting bats and will generally feed on humans only if the bats leave the premises. If the blood-feeder is a bat bug rather than a bed bug, a different management approach is needed. In other instances, insects that share similar appearances are misidentified as bed bugs. For example, carpet beetles and their shed exoskeletons are often confused for bed bugs because they share similar appearances and are found in similar areas of the house.

Control of bed bugs is best achieved by following an integrated pest management (IPM) approach that involves multiple tactics, such as preventive measures, monitoring, sanitation, and chemicals applied to targeted sites. Infestations usually are best handled by a licensed pest management professional and often require more than one treatment.

Prevention

Do not accidentally bring infested items into one's home. It is important to carefully inspect clothing and baggage of travelers, being on the lookout for bed bugs and their telltale fecal spots. Also, thoroughly inspect secondhand beds, bedding, and furniture and avoid any items that have evidence of current or past bed bug infestations. Some secondhand stores treat large items before selling, however this is not the norm. Additionally, picking up items from the curb greatly elevates the risk to the home where the items are taken. Caution is strongly warranted against secondhand items that cannot be verified as free from bed bugs. In the home, cracks and crevices in the building’s exterior should be caulked, and openings should be repaired or screened to exclude birds, bats, and rodents that can serve as alternate hosts for bed bugs.

Inspection

A thorough inspection of the premises to locate bed bugs and their harborage sites is necessary so that cleaning efforts and insecticide treatments can be focused. Inspection efforts should concentrate on the mattress, box springs, and bed frame, as well as cracks and crevices that the bed bugs may hide in during the day or when digesting a blood meal. The latter sites include window and door frames, floor cracks, carpet tack boards, baseboards, electrical boxes, furniture, pictures, wall hangings, drapery pleats, loosened wallpaper, cracks in plaster, and ceiling moldings. Determine whether birds or rodents are nesting on or near the house.

When traveling, it is important to inspect your hotel or rental for signs of bed bugs. In hotels, apartments, and other multiple-type dwellings, it is advisable to also inspect adjoining units because bed bugs can travel long distances. Using a flashlight, look for bed bug feces, shed exoskeletons and live insects in cracks, crevices, seams and other tight places that serve as hiding spots. If bed bugs or signs of bed bugs are found, do not stay in that room. Ask to be moved to a room that is not adjacent to the room containing bed bugs. It is recommended that you unpack as little as possible during your travels and your belongings should be kept out of provided wardrobes and off upholstered surfaces.

Sanitation

Sanitation measures include frequently vacuuming the mattress and premises, laundering bedding and clothing in hot water and drying on high heat, and cleaning and sanitizing dwellings. After vacuuming, immediately place the vacuum cleaner bag in a plastic bag, seal tightly, and discard in a container outdoors. This procedure prevents captured bed bugs from escaping into the home. Alternatively, a nylon stocking can be placed between sections of the vacuum wand to collect bed bugs and prevent them from entering the vacuum bag (Figure 4). A video demonstrating the vacuuming process can be found at https://youtu.be/c3Gd7qYmp_c. It should be noted that the stocking should be immediately tied off when the vacuum is turned off, removed from the wand, and disposed of in a tightly sealed bag. A stiff brush or card can be used to scrub the mattress seams to dislodge bed bugs and eggs. If a mattress is discarded, it should be done so only after being treated, as a new mattress can quickly become infested if bed bugs are still on the premises and bed bugs can be transferred to other parts of the building when moving the mattress. If a mattress is deemed unusable after treatment, it should be wrapped in plastic before being taken out of the building and defaced/destroyed so that it is not reused by anyone else. Steam cleaning of mattresses is generally not recommended because it is difficult to get rid of excess moisture, which can lead to problems with mold, mildew, house dust mites, etc.

Repair cracks in plaster and glue down loosened wallpaper to eliminate bed bug harborage sites. Remove and destroy wild animal roosts and nests in the building or ceiling when possible. 

Drawing showing how to attach a nylon stocking to the wand of a vacuum cleaner to contain bed bugs

Figure 4. Modification to a vacuum cleaner to assist in the removal of bed bugs. Source: Jones and Boggs. 2001. OSU Fact Sheet HYG-2158.

Exclusion/Trapping

After the mattress is vacuumed or scrubbed, it can be enclosed in a zippered mattress cover (encasement) designed to trap any remaining bed bugs inside the cover as long as the cover remains zipped and there are not holes, tears, or rips in the cover. The mattress should remain encased, as bed bugs can live for six months or more without a blood meal.

Sticky traps are not always effective in monitoring for bed bug presence. Conversely, passive pitfall monitors (“interceptors”) designed to go below the legs of beds and furniture are useful in early detection of bed bugs. These monitors work by trapping nymphs and adults in a depression in the monitor from which they are unable to escape. Provided there are no other ways for a bed bug to gain access to the bed, interceptors also work to reduce the likelihood that a bed bug can climb a bed without becoming stuck in an interceptor.

Insecticides

The recent rise in bed bug infestations can be attributed to a combination of factors, but insecticide resistance is one of the biggest contributors. Historically, pyrethroids were one of the best defenses against bed bugs, as they were effective, provided residual protection, and were widely available. However, this led to overuse and misuse, resulting in the development of highly resistant strains of bed bugs to pyrethroids. Pyrethroid compounds are still used but are generally applied in conjunction with other synergistic insecticides.  

Compounds such as silica gel and diatomaceous earth have shown promise in effectively controlling bed bugs. They work though disrupting the insect exoskeleton, thereby causing death by dehydration. This control method is not rapid, sometimes taking weeks to fully work, yet it is generally highly effective. Regardless of the insecticide(s) used, it is important that the treatment is tailored to each specific situation and targeted area. Certain insecticides are better suited for spot treatments, while others are more effective for treating voids and cracks. These considerations should be made when implementing any IPM program.

There is often a tendency for people to attempt do-it-yourself (DIY) treatments for bed bugs. Over-the-counter total-release foggers (“bug bombs”) are marketed as treatments for infestations, yet studies show they are not effective at penetrating into bed bug harborage sites and generally do not kill bed bugs even with direct contact to the insecticide. Others try to treat with natural or “green” products, but these are exempt from registration by the EPA and are not required to demonstrate efficacy. Therefore, many claims made by these manufacturers are unsubstantiated and can simply exacerbate at bed bug problem. Surveys conducted by The Ohio State University show that unlicensed individuals/homeowners misuse a variety of chemicals to treat bed bugs, including outdoor pesticides, petroleum products, and alcohol. These are not only ineffective but are also dangerous as they may be toxic and/or highly flammable. 
 
Since the resurgence of bed bugs in the early 1990s, there have been approximately 12 classes of insecticides that have been evaluated for bed bug control. The efficacy of insecticide control of bed bugs varies based on many factors, including the strain of bed bug being targeted, susceptibility of the strain to that particular insecticide, and insecticide dosage. It is for these reasons that bed bug infestations are most effectively controlled by professional pest management companies that are well versed in the most current control methods.

Additional Resources

      
The original version of Bed Bugs fact sheet HYG-2105-04 was published in 2004 and written by Susan C. Jones, PhD, Professor of Entomology (Retired).

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