B
Species Profile

Bed Bugs

Cimex lectularius

Flat, fast, and hard to spot
Dmitry Bezrukov/Shutterstock.com
bed bug on mattress

At a Glance

Found Worldwide
Also Known As bedbug, night bug, chinche de cama, punaise de lit, Bettwanze, percevejo-de-cama, bedwants
Diet Sanguivore
Activity Nocturnal
Lifespan 6 years
Weight 3.0E-5 lbs
Status Not Evaluated
Did You Know?

Adults are ~4.5-7.0 mm long and dorsoventrally flattened-about the size of an apple seed.

Size Comparison

Human 5'8"
Bed Bugs 0 in

Bed Bugs stands at 0% of average human height.

Scientific Classification

The common bed bug is a small, wingless, blood-feeding true bug that primarily feeds on humans and is a well-known household pest. It hides in cracks/crevices near sleeping areas and emerges mainly at night to feed.

Kingdom
Animalia
Phylum
Arthropoda
Class
Insecta
Order
Hemiptera
Family
Cimicidae
Genus
Cimex
Species
Cimex lectularius

Distinguishing Features

  • Small, dorsoventrally flattened body (adult typically ~4–7 mm), oval shape
  • Reddish-brown coloration; becomes more swollen and darker after feeding
  • Wingless (no functional wings), with short vestigial wing pads
  • Piercing-sucking mouthparts (Hemiptera) adapted for blood-feeding
  • Often detected by fecal spotting, shed skins, and characteristic harborages near beds

Physical Measurements

Males and females differ in size

Height
♂ 0 in (0 in – 0 in)
Length
♀ 0 in (0 in – 0 in)
Weight
♂ 0 lbs (0 lbs – 0 lbs)
♀ 0 lbs (0 lbs – 0 lbs)
Top Speed
0 mph
Walking about 0.075 km/h

Appearance

Primary Colors
Secondary Colors
Skin Type Chitinous exoskeleton; strongly dorsoventrally flattened when unfed, becoming swollen/elongate after feeding. Wingless externally (only wing pads/vestiges present), with short, broad pronotum and a beak-like piercing-sucking rostrum (Hemiptera) (Usinger 1966).
Distinctive Features
  • Adult size: commonly ~0.5-0.7 cm long (unfed); body broadly oval and very flat when unfed, enabling tight crack/crevice harborages (Usinger 1966; CDC).
  • Egg size: ~0.1 cm long, whitish/cream; laid in concealed sites near sleeping areas (Usinger 1966).
  • Life cycle: egg to 5 nymphal instars to adult; each nymphal molt typically requires at least one blood meal (hematophagy) (Usinger 1966).
  • Active at night and hidden by day in mattress seams, bed frames, baseboards and wall voids, the common bed bug emerges to feed using cues like CO2, heat, and human smell.
  • Feeding: obligate blood-feeder; both sexes and all mobile stages feed. A typical meal can take several minutes, and the abdomen visibly distends and darkens red after feeding (Usinger 1966).
  • Human-associated indoor habitat and dispersal: strongly synanthropic; commonly transported passively via luggage, bedding, furniture, and other belongings rather than active long-range movement (Usinger 1966; Doggett et al. 2018).
  • Compared to Cimex lectularius, bat bugs have longer pronotal fringe hairs (setae) that extend beyond eye width, while Cimex lectularius has shorter setae; you often must look under a microscope.
  • Cimex lectularius (common bed bug) is not seen as a major carrier of human disease under normal conditions. Some germs were found in lab tests, but it is not a significant public health threat.
  • Longevity/survival without feeding varies strongly with temperature and life stage; adults and late instars can persist for months under cool conditions, contributing to persistence in vacant rooms (Usinger 1966).

Sexual Dimorphism

Sexes are similar in overall coloration and size range, but differ in terminal abdominal shape and reproductive structures; dimorphism is most evident in the posterior abdomen and genital region (Usinger 1966).

♂
  • Posterior abdomen more pointed/narrow; male genital capsule visible ventrally near the tip (Usinger 1966).
  • Traumatic insemination organ (male intromittent organ/paramere) associated with mating; not externally obvious without close inspection but reflected in terminal abdominal morphology (Usinger 1966).
♀
  • Posterior abdomen typically broader and more rounded than male (Usinger 1966).
  • Female has the ectospermalege (specialized mating scar/structure) on the right side of the abdomen, an adaptation to traumatic insemination; location is diagnostic on close examination (Usinger 1966).

Did You Know?

Adults are ~4.5-7.0 mm long and dorsoventrally flattened-about the size of an apple seed.

Females typically lay ~1-7 eggs/day and can produce ~200-500 eggs over a lifetime (temperature/feeding dependent).

Eggs are ~1 mm long; at warm room temperatures (~25-30 °C), egg-to-adult development can be ~5-8 weeks with regular blood meals.

There are 5 nymphal instars, and each molt requires a blood meal (hematophagy is tied directly to growth).

A single meal often takes ~3-10 minutes; bugs usually feed at night, then retreat to tight harborages.

They can persist through long fasts: well-fed stages commonly survive weeks to months without feeding (longer in cooler conditions).

Mating is via traumatic insemination-males pierce the female's abdomen, a notorious reproductive strategy among cimicids.

Unique Adaptations

  • Piercing-sucking mouthparts (Hemiptera) form a beak-like rostrum that injects saliva and draws blood efficiently.
  • Saliva contains pharmacologically active compounds (including anticoagulant/vasodilatory and anesthetic effects) that help maintain blood flow and reduce immediate detection in many people.
  • Extreme flattening and flexible cuticle allow entry into very thin gaps (harborages only slightly wider than the bug's body).
  • Starvation tolerance: metabolic downshifting enables survival for long periods without feeding, aiding persistence in vacant rooms.
  • Rapid, temperature-dependent development enables population surges in warm indoor environments.
  • Cuticular/behavioral resistance toolkit: populations worldwide have evolved resistance to multiple insecticide classes; behaviorally, they avoid treated surfaces and favor protected refuges.
  • Species-level ID vs similar cimicids (bat bugs): common bed bugs (C. lectularius) have shorter pronotal fringe setae than bat bugs (e.g., Cimex adjunctus), whose pronotal hairs are conspicuously longer-often cited as longer than the bug's eye width; bat bugs are also more associated with bat roosts than human beds.

Interesting Behaviors

  • Nocturnal host-seeking: emerges mainly pre-dawn, guided by COâ‚‚, body heat, and human odors, then returns to shelter after feeding.
  • Harborage ecology: aggregates in cracks/crevices (mattress seams, bed frames, baseboards, behind headboards) where bodies fit tightly against surfaces.
  • Aggregation signaling: cluster using chemical cues; fecal spotting and odors can mark recurring refuges.
  • Feeding-molting linkage: nymphs typically seek a blood meal before each molt; delays in feeding can stall development for extended periods.
  • Passive dispersal: spreads primarily by hitchhiking in luggage, used furniture, bedding, and clutter rather than long-distance active movement.
  • Startle/avoidance behavior: prefers darkness and tight spaces; when disturbed may scatter to nearby crevices rather than remain exposed.
  • Opportunistic host use: primarily human-associated indoors, but will feed on other warm-blooded hosts if humans are unavailable.

Cultural Significance

Cimex lectularius (common bed bug) is a known indoor pest in temperate areas. It shaped bed design, laundry, and fumigation. Its late 20th–21st century return—from travel, used furniture, and insecticide resistance—made it a public health problem, led to hotel and housing inspections, and remains in the "Sleep tight" rhyme.

Myths & Legends

"Sleep tight, don't let the bed bugs bite": a widely repeated Anglo-American bedtime rhyme/wish that treats bed bugs as the archetypal night-biting nuisance to be warded off before sleep.

Name lore: the species epithet lectularius comes from Latin lectus ("bed"), reflecting a long cultural association with sleeping spaces and the idea of a creature 'born of the bed.'

People in old Europe thought common bed bugs (Cimex lectularius) hid in old beds, wall cracks, and damp wood, so they burned, smoked, or sealed frames to drive them out.

In parts of Europe, old stories say the common bed bug (Cimex lectularius) was used in home remedies, which made people think these pests had strong effects—either harmful or healing.

Seafarers' and travelers' stories long cast bed bugs as stowaway 'shipmates' that follow people from inns and ports, a narrative that mirrors their real-world hitchhiking dispersal in baggage and bedding.

Conservation Status

NE Not Evaluated

Has not yet been evaluated against the criteria.

Population Unknown

Life Cycle

Birth 1 nymph
Lifespan 6 years

Lifespan

In the Wild
2–12 years
In Captivity
3–18 years

Reproduction

Mating System Promiscuity
Social Structure Aggregation Group
Breeding Pattern Transient
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Cimex lectularius mates in dense indoor harborages (cracks/crevices). Both sexes mate repeatedly with many partners; males use traumatic insemination into the spermalege. Females store sperm and lay eggs (no care); nymphs pass five instars; adults live ~6–12 months.

Behavior & Ecology

Social Harborage (aggregation) Group: 100
Activity Nocturnal
Diet Sanguivore Human blood (Homo sapiens)
Seasonal Hibernates

Temperament

Cryptic and strongly thigmotactic (prefers tight crevices/contact surfaces)
Gregarious (aggregation-prone) rather than territorial
Non-aggressive toward conspecifics; interactions mainly involve crowding/harborage sharing
Sexually antagonistic mating system: traumatic insemination; males may harass and attempt copulation frequently within aggregations (Reinhardt & Siva-Jothy 2007)
Host-seeking is opportunistic; will feed in daytime under starvation/disturbance or when host availability dictates, despite a primary nocturnal rhythm (Usinger 1966)

Communication

aggregation pheromones Chemical cues from feces/exuviae and associated volatiles) promote clustering and harborage fidelity; documented attraction to aggregation-associated chemicals (Siljander et al. 2008
alarm pheromone released when disturbed: a blend dominated by E)-2-hexenal and (E)-2-octenal triggers dispersal/avoidance (e.g., Levinson et al., 1974; Harraca et al., 2012
contact chemoreception via cuticular hydrocarbons and other body-surface chemicals used in close-range recognition/sexual interactions Reinhardt & Siva-Jothy 2007
host-location uses kairomones/physical cues (COâ‚‚, heat, human odor components) rather than social signals; individuals in a harborage may become active in parallel when host cues rise

Habitat

Biomes:
Temperate Forest Mediterranean Temperate Grassland Boreal Forest (Taiga) Tundra Alpine Desert Hot Desert Cold Tropical Rainforest Tropical Dry Forest Savanna Wetland +6
Elevation: Up to 7726 ft 5 in

Ecological Role

Obligate hematophagous ectoparasite of humans and other warm-blooded animals; primarily an indoor/commensal parasite and significant household pest.

Parasitism: removes small amounts of host blood and can alter host behavior/sleep through biting and allergic reactions (nuisance and health-impact role rather than a beneficial service). Trophic link in indoor ecosystems: serves as prey for arthropod predators/scavengers in human dwellings (e.g., spiders, ants, cockroaches), transferring vertebrate-derived nutrients into invertebrate food webs. Population/occupancy indicator: presence can indicate availability of warm-blooded hosts and suitable indoor refugia (used in monitoring/inspection contexts).

Diet Details

Main Prey:
Human Other mammals Birds and bats

Human Interaction

Domestication Status

Wild

Cimex lectularius (common bed bug) is a wild, human-associated parasite, not a domesticated species. It likely moved from bats and birds to people when humans used caves and later homes. Today it is well adapted to indoor life and travel. Other Cimicidae species also bite or infest near bat or bird roosts.

Danger Level

Moderate
  • Bites causing pruritic wheals/papules; reactions range from minimal to severe allergic responses (including rare anaphylaxis) (Doggett et al. 2018).
  • Secondary bacterial infection from scratching (impetiginization/cellulitis risk).
  • Sleep disturbance and psychological effects (stress, anxiety, insomnia) reported in infestations (Doggett et al. 2018).
  • Not considered a confirmed, important vector of human disease under natural conditions despite pathogen detection in some studies (Doggett et al. 2018).
  • Infestation spread via human travel and movement of furniture/luggage; hides in cracks/crevices near sleeping areas and typically feeds at night.

As a Pet

Not Suitable as Pet

Legality: Not regulated as a conventional pet; however, intentional possession/transport may violate local public-health, housing, or pest-control regulations and can trigger civil liability. Many institutions (schools, labs, landlords) explicitly prohibit keeping/transporting bed bugs outside permitted research/containment.

Care Level: Expert Only

Purchase Cost:
Lifetime Cost:

Economic Value

Uses:
Negative economic impact (household pest; remediation costs) Public health / mental health burden (sleep disruption, anxiety, stigma) Scientific and educational value (insect physiology, insecticide resistance, host-parasite interactions) Pest management industry demand (inspection, heat treatment, insecticides, mattress encasements)
Products:
  • Pest control services (inspection, canine detection, heat treatment, fumigation where permitted)
  • Insecticides and desiccant dusts (e.g., silica gel/diatomaceous earth products used in IPM)
  • Monitoring devices (interceptors, COâ‚‚/heat lures, traps)
  • Protective/containment products (mattress/box-spring encasements, climb-up interceptors)

Relationships

Predators 6

Masked hunter Reduvius personatus
House centipede Scutigera coleoptrata
Pharaoh ant Monomorium pharaonis
German cockroach
German cockroach Blattella germanica
American cockroach
American cockroach Periplaneta americana
Common house spider
Common house spider Parasteatoda tepidariorum

Related Species 5

Tropical bed bug Cimex hemipterus Shared Genus
Bat bug Cimex pipistrelli Shared Genus
Bat bug Cimex adjunctus Shared Genus
Pigeon bug Cimex columbarius Shared Genus
Cliff swallow bug Oeciacus vicarius Shared Family

Ecological Equivalents 5

Animals that fill a similar ecological role in their ecosystem

Human flea Pulex irritans Like Cimex lectularius, it is a hematophagous ectoparasite strongly associated with human dwellings and hosts, typically feeding at night and persisting in cracks and soft furnishings. Both cause pruritic bites and can survive extended periods between blood meals relative to many other biting insects.
Human body louse Pediculus humanus humanus Obligate human blood-feeder that takes repeated brief feedings and is closely associated with sleeping/resting humans. Parallels bed bugs' reliance on human blood but differs by living on clothing and skin rather than in harborages.
Common mosquito Culex pipiens Nocturnally active, blood-feeding insect that frequently bites humans indoors. Ecologically similar as a human-biting hematophage, although mosquitoes are volant and do not permanently harbor in crevices near beds.
Kissing bug
Kissing bug Triatoma infestans Crevice-dwelling, nocturnal hematophagous true bug (Hemiptera) that feeds on sleeping hosts and hides in cracks in human structures. Convergent niche similarity with Cimex lectularius: both exhibit night-time feeding, use harborages, and take intermittent large blood meals.
Bat bug Cimex spp. Very similar life-history strategy: wingless, crevice-hiding, nocturnal blood-feeder. Primarily associated with bats, but often invades human sleeping areas when bat hosts are absent, functionally occupying an almost identical niche in buildings.

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The bed bug is an insect that feeds on blood and is most active at night. True to its name, the bed bug is most common in beds. These insects are notoriously difficult to get rid of. These parasitic insects are members of the genus Cimex. Their bites cause skin rashes, but may also cause psychological effects and allergic reactions.

Species, Types, and Scientific Name

Of the insects in the genus Cimex, two species cause infestations of bed bugs:

  • Cimex lectularius – Also known as the common bed bug. While these can be in the same location as the tropical bed bug, they typically are not in the same warm areas. But bed bugs can be found wherever their hosts can be found.
  • Cimex hemipterus – Also known as the tropical bed bugs. These are very similar in appearance to the common bed bug and have similar characteristics, and they obviously live in tropical climates.
  • Leptocimex boueti – As a result, populations of this type of bed bug are contained in South America and West Africa. This is partially due to the fact that humans actually aren’t the primary prey for this species of the bed bug. Most members of Leptocimex boueti feed off of bats rather than humans, although they’re not choosy eaters.

There are 11 subspecies of the genus Cimex. Only four out of 90 species of bed bugs feed on humans, with the aforementioned two preferring humans. The others are bat bugs.

What Do Bed Bugs Look Like
Four out of 90 subspecies of bed bugs feed on humans.

Appearance

Proper identification of bed bugs rules out confusion with other insects such as fleas, ticks, carpet beetles, and cockroaches. It also depends on the life stage of the bed bugs.

Adult bed bugs are five to seven millimeters long — about the size of an apple seed — and visible to the naked eye. They are brown and long with an oval-shaped, flat body unless it’s recently fed. If it’s fed, its body is round, reddish-brown in color, and longer. As true insects, they have beaks with three segments, an antenna with four parts, wings that aren’t for flying, short, golden hairs, and a sweet-musty odor coming from glands on their undersides.

These insects have five immature or young life stages called nymphs before they become adults. Nymphs are smaller and either whitish-yellow or translucent depending on whether they’ve fed recently or not.

Bed bug eggs are pearly-white and tiny, about the size of a pinhead. If more than five days old, they have an eyespot marking.

Rather than the identification of live bed bugs, however, identification may instead mean recognizing an infestation. This is usually from early signs such as bites or spots of human blood. You may also see rusty stains from crushed bed bugs, dark spots from excrement, or pale yellow eggs and eggshells.

Early signs of bed bugs are uncomfortable, itchy nights in bed, marks on arms and shoulders, and an unpleasant odor resembling a wet towel. Symptoms of bed bug bites are skin rashes of red, itchy, flat welts in zigzag lines or clusters. The bites have a darker red spot in the middle. Some people may have allergic reactions and develop fever, severe itching, blisters, or hives. They can also cause secondary bacterial infections such as impetigo, lymphangitis, and ecthyma, as well as symptoms of psychological issues such as insomnia and anxiety.

Read this guide on how to identify bed bugs for more information.

Bed bugs feed on human blood.

History and Evolution

When it comes to evolution, it is always important to factor in what the animal ate and what was in its diet. This is because survival ability dictates adaptation and supports evolution towards being more successful at obtaining that food source. It is especially important for animals like bed bugs that require a host to feed.

Specific species of bed bugs are generally known to feed on four different types of hosts: humans, bats, water birds, and other birds. This is because they have evolved to become very adept at feeding off them. As researchers are finding, however, the history of the bed bug ancestry dates back many millions of years ago and predates some of their current hosts, like humans. Scientists are working on solving the puzzle of how these insects were able to make the jump between different types of hosts over their evolution.

Habitat

The habitat of these insects is worldwide, never in nature. Instead, they live in mattresses, fabrics, furniture, luggage, and pieces of wood. They hide from light and movement during the day and come out at night, so they wait in seams of furniture, curtain folds, electrical appliances, the junction of the wall and ceiling, loose wall hangings and wallpaper, and even in heads of screws. They can live singly but come together in clusters in their habitat.

Bed bugs - signs on mattress

Bed bugs live in mattresses and fabrics.

Diet

The diet of bed bugs is blood. Some species prefer the blood of one mammal over another in their diet, while others absolutely need the blood of a specific mammal to survive and lay viable eggs. Those that humans deal with as pests in homes, apartment buildings, and offices feed on human blood. Their bites don’t hurt at first because they inject an anesthetic while they are feeding, which is four to 12 minutes. Plus, they feed during the night, when it is dark and humans are asleep. Their bites most often appear on the neck, face, arms, and hands.

How Big Are Bed Bugs Compared to Other Bugs Poster Image
Bed bugs feed on their hosts at night.

Prevention

To get rid of these insects more easily and quickly, noticing the early signs of bed bug infestation or symptoms of bed bug bites is important. Professionals first use visual inspection, then sniffing dogs, interceptor cups, and insect monitor cards. Average people, however, need methods that don’t require a lot of money. Read our complete guide on how to get rid of bed bugs for more information.

To get rid of them, laundering and drying with heat is one method. Vacuuming and steam treatment are others. Commercial heating services offer whole-room heat or cold treatments to kill them. You can either heat a room at 140 degrees Fahrenheit for two hours or 130 degrees Fahrenheit for three hours. Cold treatment isn’t possible or practical except through commercial heating services. If you’re getting rid of infested furniture, make sure they’re unusable so other people won’t spread bed bugs to their own homes.

Finally, there are chemical treatments. Pesticides can be effective but need to be handled very carefully, and bed bugs can become resistant. They cannot be used on items that people come into contact with. Liquid and dry formulas should only be applied to cracks and crevices. They may include insect growth regulators as well as desiccants, which dry out these insects. They must be registered by the EPA and labeled specifically for bed bug control.

Bed Bugs Exterminator - professional

Bed bugs exterminators use gloves and safety glasses to inspect infected mattress sheets and blanket bedding.

An alternative is the use of botanical oils, which are plant-based insecticides. Certain neem oil insecticides are registered for bed bug control.

As for how to prevent them in the future, a mattress encasement will protect your bed. It covers both the mattress as well as the box spring. Diatomaceous earth and pheromone traps work on everything else. It is difficult to find how to prevent bed bugs with just one method, though, so it’s best to use them together. We recommend all of the items below be used in conjunction for the most effective bed bug prevention.

  1. Bed Bug Killer by Ecovenger 16 oz
    • USDA BioBased formula is child and pet friendly
    • 100% effective per recent study
    • Kills bed bugs at all stages - adults, nymphs, and eggs
    Check Amazon
  2. SureGuard Bed Bug Mattress Encasement
    • Effective encasement against bed bugs
    • Waterproof - doubles as a mattress protector
    • Invisi-Zip and SureSeal enclosure ensures no bed bug entry
    • 100% Cotton top - free from phthalates and other unhealthy chemicals
    Check Amazon
  3. HARRIS Bed Bug Traps - (20-Pack)
    • No chemical option to confirm bed bug presence
    • Catches other bugs and pests as well
    • Easy detection coverage for 2-3 rooms.
    Check Amazon
  4. EcoPest Bed Bug Interceptors 8 Pack
    • No chemical solution to block bed bugs
    • Easy application
    • Effective blockers for other pests like spiders
    Check Amazon
  5. Queen Mattress, Novilla 10 inch Gel Memory Foam Mattress
    • 10 inch gel mattress is very comfortable
    • Easy to apply encasement compared to wood frame mattresses
    • Fast shipment and easy to install vs traditional optionss
    Check Amazon
  6. Housmile Bed Vacuum Cleaner, UV Handheld
    • Powerful 10Kpa suction sucks up dust mites
    • Specialized design for cleaning mattresses
    • UV lamp eliminates moisture and kills bacteria


    Check Amazon
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Sources

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  2. WhatKillsIt / Accessed January 1, 2022
  3. Wikipedia / Accessed January 1, 2022
  4. Wikipedia / Accessed January 1, 2022
  5. Terminix / Accessed January 1, 2022
  6. USEPA / Accessed January 1, 2022
  7. Terminix / Accessed January 1, 2022
  8. Mayo Clinic / Accessed January 1, 2022
  9. Thermal Bedbug Heat / Accessed January 1, 2022
  10. Treating Bruises / Accessed January 1, 2022
  11. Dominion Pest Control / Accessed January 1, 2022
  12. Terminix / Accessed January 1, 2022
  13. PetSeek / Accessed January 1, 2022
  14. DoMyOwn / Accessed January 1, 2022
  15. Penn State Extension / Accessed January 1, 2022
  16. Bed Bug Lawyers / Accessed January 1, 2022
  17. Bed Bug Lawyers / Accessed January 1, 2022
  18. Pestivate.com / Accessed January 1, 2022
  19. Terminix / Accessed January 1, 2022
  20. Pest Stop Solutions / Accessed January 1, 2022
  21. USEPA / Accessed January 1, 2022
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  23. TreatingBruises / Accessed January 1, 2022
Heather Ross

About the Author

Heather Ross

Heather Ross is a secondary English teacher and mother of 2 humans, 2 tuxedo cats, and a golden doodle. In between taking the kids to soccer practice and grading papers, she enjoys reading and writing about all the animals!

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Bed Bugs FAQs (Frequently Asked Questions)

Adult bed bugs can be seen with the naked eye. They are small, long, and brown, about the size of apple seeds.