How can you tell if there are bedbugs in an apartment?

Understanding Bed Bugs

What Are Bed Bugs?

Characteristics and Appearance

Bedbugs are oval, flat insects about 4–5 mm long when fully grown. Their bodies are reddish‑brown, darkening after a blood meal. Nymphs are smaller, translucent to pale yellow, and become progressively darker with each molt. The head, antennae, and legs are clearly visible, and the dorsal surface lacks wings or noticeable hairs.

Visible evidence of an infestation includes:

Live adult or nymph specimens, often found in mattress seams, box‑spring folds, or along baseboards.
Exuviae (shed skins) left behind after each molt; these are translucent shells matching the insect’s shape.
Dark, rust‑colored fecal spots resembling small ink stains on fabrics, sheets, or walls.
Tiny, white, oval eggs attached to seams, folds, or crevices; they measure about 0.5 mm in length.
Small, reddish spots on bedding caused by crushed bugs or minor blood leakage.

These characteristics enable reliable identification of a bedbug presence without reliance on anecdotal descriptions.

Life Cycle and Habits

Bedbugs progress through five developmental stages: egg, first‑instar nymph, second‑instar nymph, third‑instar nymph, fourth‑instar nymph, and adult. Each nymph requires a blood meal to molt to the next stage, and the entire cycle can be completed in as little as four weeks under optimal conditions.

Temperature governs the speed of development. At 80 °F (27 °C) the cycle averages 21 days; at lower temperatures, development slows markedly, extending the period to several months. Adults may live for 6–12 months, feeding repeatedly throughout their lifespan.

Feeding occurs exclusively at night, when the insect seeks a host’s exposed skin. After a blood meal, the insect retreats to a concealed site to digest and, if necessary, molt. The presence of fresh or old blood stains on sheets, small dark spots of excrement, and shed exoskeletons indicates recent feeding activity.

Bedbugs favor flat, protected surfaces near sleeping areas. Typical refuges include mattress seams, box‑spring folds, headboard cracks, baseboard crevices, upholstered furniture, electrical outlet covers, and behind picture frames. Their flattened bodies allow them to infiltrate minute gaps, making detection difficult without close inspection.

Common evidence of infestation, linked to their life cycle and habits:

Tiny, rust‑colored fecal spots on bedding or walls
Tiny, translucent eggs (≈ 1 mm) deposited in clusters
Molted skins (exuviae) near hiding sites
A sweet, musty odor emitted by large colonies
Bites appearing in linear or clustered patterns on exposed skin

Recognizing these signs in relation to the insect’s developmental timeline and preferred harborage points enables reliable identification of a bedbug problem within an apartment.

Signs of an Infestation

Visual Evidence

Live Bed Bugs

Live bed bugs are small, wingless insects that feed on human blood. An adult measures 4–5 mm, flat, reddish‑brown, and becomes more swollen and darker after feeding. Nymphs resemble adults but are lighter and smaller; they molt five times before reaching maturity. All stages move quickly across fabric and hide in protected crevices.

Visible evidence of an infestation includes:

Tiny, rust‑colored spots on bedding or furniture, representing digested blood.
Shedding skins (exuviae) left behind as nymphs grow.
Small, white eggs about 0.5 mm in length attached to seams, folds, or baseboards.
Live insects spotted on mattress seams, box‑spring edges, headboards, or behind picture frames.

Behavioral clues help confirm activity. Bed bugs emerge at night, clustering near sleeping areas. A faint, sweet, musty odor may develop in severe cases due to their defensive glands.

Effective inspection requires systematic examination. Remove bedding and inspect the mattress underside, paying particular attention to seams and tufts. Use a flashlight to probe cracks in headboards, nightstands, and baseboard joints. Examine upholstered furniture by lifting cushions and checking the interior folds. For thoroughness, inspect behind electrical outlets, under wall hangings, and in luggage racks if recent travel is suspected.

Detecting live bed bugs early prevents widespread colonization and reduces the need for extensive treatment. Regular visual checks, especially after staying in hotels or using shared accommodations, remain the most reliable method for confirming their presence.

Bed Bug Eggs

Bed bug eggs, often called “cocci,” are tiny, oval-shaped structures about 0.5 mm in length. Their color ranges from white to pale yellow, darkening to brown as the embryo develops. Eggs are firmly attached to surfaces with a cement‑like secretion, making them difficult to dislodge.

Typical locations include:

seams of mattresses, box springs, and pillowcases
folds and creases of furniture upholstery
baseboards, wall cracks, and behind picture frames
luggage tags, luggage straps, and suitcase interiors

During an inspection, look for clusters of eggs in these areas. A magnifying lens or smartphone camera with macro capability can reveal the subtle sheen of fresh eggs. Lightly tapping the suspected surface may cause eggs to shift slightly, confirming their presence.

The presence of eggs indicates an active infestation, even if adult insects are not observed. Egg clusters often accompany other signs such as:

reddish‑brown spots (fecal stains) on bedding or furniture
tiny, translucent shed skins from nymphal stages
a sweet, musty odor in severe cases

Removing eggs requires thorough cleaning. Vacuuming with a HEPA‑rated filter, followed by washing fabrics at temperatures above 120 °F (49 °C), destroys most viable eggs. In sealed cracks or crevices, professional steam treatment or insecticidal application may be necessary.

Detecting bed bug eggs early prevents population growth and limits spread throughout an apartment building. Regular visual checks of the listed locations, combined with monitoring for additional indicators, provide a reliable method for confirming infestation.

Shed Skins

Detecting a bed‑bug infestation often begins with visual clues, and shed skins are among the most reliable. When nymphs grow, they leave behind translucent, oval shells about 2‑5 mm long. The shells are light brown to tan, with a glossy surface that may appear slightly wrinkled where the insect emerged.

These exoskeletons are typically found in the same locations where the insects hide: mattress seams, box‑spring folds, headboard cracks, baseboard joints, and behind picture frames. A careful inspection of these areas with a flashlight can reveal several shells clustered together, indicating recent activity.

Shed skins differ from other debris such as dust, fabric fibers, or the white, powdery droppings of cockroaches. Unlike cockroach shed skins, which are larger, thicker, and darker, bed‑bug shells are uniformly small and lack visible legs or antennae.

To confirm the presence of bed‑bugs based on shed skins, follow these steps:

Locate potential hiding spots and use a bright light to scan for translucent shells.
Collect any suspected shells with a piece of tape or tweezers.
Compare the collected material to reference images of bed‑bug exuviae, noting size, shape, and coloration.
If shells match the description, expand the search to adjacent furnishings and repeat the inspection.

Finding multiple shed skins in a confined area strongly suggests an active infestation and warrants immediate pest‑control measures.

Fecal Stains («Black Spots»)

Fecal stains appear as small, dark‑brown to black specks on bedding, mattress seams, headboards, and nearby furniture. The spots are the digested blood remnants excreted by bedbugs after feeding. They differ from dust or fabric dye because they are irregular, have a matte finish, and do not wash out easily.

Typical characteristics:

Size: 0.5–2 mm in diameter.
Color: deep brown, almost black; may fade to reddish‑brown when exposed to light.
Texture: dry, powdery, may crumble under gentle pressure.
Location: concentrated near sleeping surfaces, especially along seams, folds, and creases.

Distinguishing fecal stains from other marks:

Dust or lint is lighter, loosely attached, and can be brushed away.
Ink or paint residues are glossy and may smear when touched.
Mold appears fuzzy and spreads over larger areas.

To confirm presence of bedbugs, inspect the following:

Use a bright flashlight or a headlamp to illuminate dark corners and seams.
Run a thin, disposable card (e.g., a credit‑card) over suspect spots; fecal stains will leave a faint smear on the card surface.
Collect a sample with a clean swab and examine under a magnifying lens; bedbug feces contain digested hemoglobin, giving a characteristic reddish‑brown hue.
Cross‑reference with other indicators such as live bugs, shed skins, or tiny white eggs.

When stains are found, document their position with photographs and notify property management or a pest‑control professional. Early detection based on fecal stains reduces the risk of extensive infestation.

Blood Spots

Blood spots are a reliable indicator when assessing an apartment for bedbug activity. These stains appear as small, rust‑colored or dark red specks on bedding, mattresses, furniture, and walls. They result from the insect’s feeding process, where partially digested blood is expelled after a bite.

Typical characteristics of bedbug blood spots include:

Size ranging from 1 mm to 5 mm in diameter.
Irregular shape, often resembling a drop or smear.
Presence near seams, folds, or crevices where insects hide.
Fading to a lighter brown after several days, but remaining detectable under a bright light.

To confirm the source, inspect the following areas with a magnifying glass or a LED flashlight:

Mattress edges, especially the stitching and tag area.
Box spring seams and the underside of the bed frame.
Upholstered chairs, particularly the cushions and stitching.
Wall baseboards and behind picture frames.

Distinguish blood spots from other stains by noting their consistency and location. Food spills, ink, or rust typically have a uniform color and are found on surfaces that have been directly contacted. In contrast, bedbug stains are often accompanied by a faint, sweet odor and may be clustered near known hiding places.

When blood spots are observed, collect a sample using a sterile swab for laboratory analysis if verification is required. Early detection through these markings enables prompt treatment and prevents a larger infestation.

Physical Symptoms on Humans

Bites and Rashes

Bedbug infestations often reveal themselves through distinctive skin reactions.

Typical bite marks appear as small, red welts, usually 1‑3 mm in diameter. They commonly develop in clusters or linear patterns, reflecting the insect’s feeding habit of moving along exposed skin. The lesions may itch intensely within a few hours and can persist for several days.

Key characteristics of bedbug bites include:

Location on exposed areas such as forearms, ankles, neck, and face.
Arrangement in a “breakfast‑lunch‑dinner” line or grouped patches.
Absence of a central puncture point, distinguishing them from mosquito bites.

Rashes associated with bedbug activity may accompany the bites. The rash often presents as a raised, inflamed area surrounding the bite, occasionally forming a halo of redness. In sensitized individuals, secondary infection can cause additional swelling, crusting, or pus formation.

Differentiating bedbug reactions from other insect bites:

Mosquito bites are typically isolated, with a single puncture and a prominent central point.
Flea bites often cluster around the ankles and are accompanied by a rapid onset of intense itching.
Scabies produces burrow‑like tracks rather than discrete welts.

When multiple, line‑arranged, itchy welts appear on exposed skin, especially after nighttime exposure, the likelihood of a bedbug presence increases significantly. Prompt inspection of bedding, mattress seams, and furniture cracks is warranted to confirm the infestation.

Itchiness and Discomfort

Itchiness that appears after sleeping is often the first indicator of a possible infestation. Bedbug bites typically manifest as small, red welts clustered in linear or zig‑zag patterns. The reaction may develop within a few hours to a couple of days and can intensify with repeated exposure.

Key characteristics of the discomfort include:

Bites concentrated on exposed skin such as arms, shoulders, neck, and face.
Presence of multiple bites in a localized area, sometimes forming a “breakfast‑n‑lunch” line.
Persistent itching that worsens at night and does not subside with standard over‑the‑counter remedies.

The sensation is usually a sharp, pruritic sting rather than a painless puncture. When the skin is scratched, secondary irritation or infection may develop, leading to swelling, redness, and a burning feeling. These symptoms, combined with the visual pattern of the bites, provide reliable evidence for confirming the presence of bedbugs in a living space.

Odor

«Sweet» or «Musty» Smell

A sweet, slightly floral odor can indicate a bed‑bug infestation. The scent originates from the insects’ defensive chemicals, which are released when they are disturbed or crushed. This fragrance is often described as a faint, pleasant perfume that may be noticeable near sleeping areas, furniture seams, or luggage.

A musty, damp smell may also appear in an infested unit. The odor results from the accumulation of fecal deposits, shed skins, and mold that thrives in the moist micro‑environment created by large numbers of insects. The mustiness is typically stronger in hidden cracks, under mattresses, and behind baseboards.

Key points for identifying these odors:

Detect a subtle sweet perfume near bed frames, headboards, or nightstands.
Notice a stale, earthy scent in corners, closets, or beneath upholstered furniture.
Compare the intensity of the smell with the normal odors of the apartment; a sudden, localized increase often signals activity.
Use a clean cloth to sample air in suspect areas; a lingering sweet or musty residue suggests the presence of bed‑bugs.

If either odor is detected consistently in specific locations, further inspection—such as examining seams, mattress tags, and wall voids for live insects, eggs, or fecal spots—is warranted. Early recognition of these smells can prompt timely treatment and prevent a larger infestation.

Where to Look for Bed Bugs

Common Hiding Spots

Mattress and Box Spring

Inspect the mattress surface and interior for small, rust‑colored spots (fecal stains), dark specks (excrement), or tiny white shells (shed skins). Use a bright flashlight to examine seams, folds, and the underside of the mattress cover. Any reddish‑brown smears on the fabric may indicate crushed bugs or blood.

Check the box spring fabric and any exposed wood or metal frames. Look for the same signs—fecal spots, shells, or live insects—especially in crevices, along stitching lines, and at the corners where the spring unit meets the mattress. Remove the mattress cover if possible and inspect the inner layers; bedbugs often hide in the padding and between the springs.

Typical indicators on these components include:

Live bugs, usually 4–5 mm, reddish‑brown, flat‑oval shape.
Tiny dark spots (excrement) that may appear as peppered specks.
White or translucent exoskeleton fragments, often found near seams.
Small blood‑colored stains, especially after a night’s sleep.
A faint, sweet, musty odor in heavily infested cases.

If any of these evidence items are present on the mattress or box spring, the likelihood of an infestation is high. Promptly isolate the bedding, wash all linens at high temperature, and consider professional treatment to prevent spread to surrounding furniture and walls.

Bed Frame and Headboard

Inspect the bed frame and headboard for the most reliable signs of infestation. Bedbugs often hide in the seams, joints, and cracks of wooden or metal frames, as well as behind the headboard’s upholstery. Look for tiny dark spots (fecal stains) along the edges, as well as shed exoskeletons that may accumulate in screw holes or under decorative molding.

Examine the underside of the mattress and the perimeter of the frame for live insects, which appear as reddish‑brown, oval bodies about 5 mm long.
Pull back any fabric covering the headboard; check the interior for live bugs, eggs, or molted skins.
Use a flashlight or a magnifying glass to inspect tight corners, bolts, and any decorative carvings where insects can conceal themselves.
Run a clean, white cloth over seams; any reddish or black specks transferred to the cloth indicate fecal matter.

If any of these indicators are present, consider treating the entire sleeping area, including the frame and headboard, before attempting to eradicate the infestation.

Furniture Near the Bed

Inspecting the furniture that surrounds the sleeping surface is essential when evaluating a possible bedbug problem. These items provide easy access for insects seeking blood meals and often conceal evidence of activity.

Live insects: small, reddish‑brown, oval bodies, 4–5 mm long, visible on surfaces or under cushions.
Exuviae: translucent shells left after molting, typically found along seams or folds.
Fecal spots: dark, pepper‑like specks on fabric, wood, or mattress frames.
Blood stains: faint reddish marks on sheets, pillowcases, or upholstery after the bug is crushed.
Odor: sweet, musty scent produced by large colonies.

A systematic inspection should include:

Remove all items from the bed area, such as nightstands, dressers, and chairs.
Use a bright flashlight to examine edges, joints, and hidden crevices.
Run a thin card or piece of tape along seams to collect any attached insects or skins.
Flip cushions and lift fabric covers to check underside surfaces.
Record any findings and photograph for documentation.

If any of the listed indicators are observed, isolate the affected furniture, wash removable fabrics at high temperature, and consider professional pest control treatment to eradicate the infestation.

Walls and Wallpaper

Walls and wallpaper often reveal early evidence of a bedbug infestation. Adult insects hide in cracks, while their eggs and shed skins accumulate on surfaces that are difficult to inspect directly.

Typical indicators on wall coverings include:

Small, rust‑colored spots where insects have been crushed.
Tiny, white specks of excrement near baseboards, electrical outlets, or picture frames.
Faint, oily stains from molted skins or eggs, especially along seams or behind trim.
Visible live bugs crawling on the wallpaper surface during daylight.

Inspecting walls requires a focused approach. Remove any hanging décor, peel back a corner of the wallpaper, and examine the underlying plaster or drywall. Use a bright flashlight at an angle to highlight shadows and discoloration. A magnifying lens can aid in spotting minute eggs (about 1 mm in length) and shed skins.

If any of the described signs appear, treat the affected area promptly. Seal cracks with caulk, replace damaged wallpaper, and consider professional heat or pesticide treatment to eradicate the hidden population. Continuous monitoring of walls, together with mattress and furniture checks, provides a comprehensive strategy for confirming a bedbug problem in a residence.

Electrical Outlets and Switches

Electrical outlets and wall switches provide discreet hiding places for bedbugs because the seams and gaps around them create protected micro‑environments. Inspecting these points reveals evidence that may be missed on visible surfaces.

When examining an outlet, first turn off power at the circuit breaker to prevent accidental shock. Remove the cover plate with a flat‑head screwdriver. Use a flashlight to look inside the box for:

Small, rust‑colored spots (fecal stains) on the wiring or plastic components.
Tiny, translucent shells shed after molting.
Live insects or clusters of eggs attached to the outlet’s edges or the switch lever.
Fine, white powder resembling mold, which can be bedbug excrement.

After the visual check, gently probe the interior with a fine brush or a disposable cotton swab. Transfer any material to a sealed container for microscopic examination. Replace the cover plate and restore power only after confirming the area is clear.

Switches present the same diagnostic opportunities. Remove the switch plate, observe the toggle mechanism, and repeat the inspection steps listed for outlets. Pay particular attention to the hinge and any recessed slots where insects might lodge.

Regularly repeating this inspection—especially after moving furniture or during seasonal pest surveys—helps confirm the absence of infestation or detect early signs before they spread.

Cracks and Crevices

Cracks and crevices in walls, baseboards, and furniture provide shelter for bedbugs. These tiny insects hide in any narrow opening that protects them from light and disturbance. When inspecting an apartment, focus on seams where paint has peeled, gaps around electrical outlets, and joints in carpet edges. Presence of live insects, shed skins, or dark spotting in these areas strongly suggests an infestation.

Key inspection points:

Baseboard seams and molding gaps
Wall cracks, especially near ceiling lines
Upholstered furniture stitching and cushion folds
Mattress tags, box‑spring corners, and headboard joints
Behind picture frames, mirrors, and wall hangings
Floorboard gaps and under floor mats

Evidence to record includes live bugs, whitish exoskeletons, and tiny rust‑colored fecal spots. Use a flashlight and a magnifying lens to examine each opening. Document findings with photos and note the exact location of any signs. This systematic approach enables reliable detection of bedbugs hidden within structural fissures.

Less Obvious Locations

Books and Clutter

Books, magazines, and paper piles create dark, undisturbed zones where bedbugs often hide. The tight seams of hardcover spines and the gaps between stacked volumes provide ideal shelter, making these items frequent blind spots during an inspection.

Typical indicators in a collection of reading material include tiny dark spots (fecal stains) on pages, shed skins, or live insects crawling on the edges of covers. A faint, sweetish odor may also emanate from heavily infested stacks. Bedbugs rarely consume paper, but they may travel through the clutter to reach nearby fabric or mattress seams.

Remove all items from shelves and examine each surface under a bright light.
Inspect the backs of book spines and the edges of pages for reddish‑brown specks.
Look for live nymphs or adults crawling on the covers, especially in the early morning when they are most active.
Shake each book gently; a sudden movement may dislodge hidden insects.
Use a magnifying glass to check the tiny cracks between stacked volumes.

Reducing the amount of paper clutter simplifies detection. Store books in sealed containers, keep shelves spaced to allow visual access, and regularly vacuum crevices. A tidy environment limits hiding places and enhances the reliability of any visual assessment for bedbug presence.

Electronics

Electronic methods provide reliable evidence of infestations without reliance on visual inspection alone. Devices such as active monitors emit carbon‑dioxide, heat, or pheromones to attract insects; captured specimens confirm presence. Portable infrared cameras reveal temperature differentials caused by clusters of insects under fabrics, allowing rapid assessment of hidden areas.

Smartphone‑compatible traps integrate sensors that count and identify bedbugs through image analysis, transmitting data to cloud‑based databases for verification. Passive glue boards equipped with embedded RFID tags record movement, enabling precise mapping of activity zones when scanned with a handheld reader.

Key electronic tools include:

CO₂‑baited traps with built‑in counting electronics
Thermal imaging units capable of detecting heat signatures through upholstery
Light‑based traps that use UV illumination to lure and immobilize insects, coupled with digital logging
Mobile applications that process microscope images captured via phone camera for species confirmation

When employing these technologies, follow calibration guidelines supplied by manufacturers, position devices near suspected harborage sites, and allow continuous operation for at least 48 hours to capture nocturnal activity. Data collected through electronic monitoring eliminates ambiguity, delivering objective proof of bedbug presence in an apartment.

Verifying an Infestation

Inspection Techniques

Using a Flashlight

Using a flashlight provides focused illumination that reveals hidden bed‑bug activity in dark or confined areas. A high‑intensity LED source, preferably with adjustable brightness, allows you to examine seams, folds, and crevices where insects hide.

Switch off room lights and close curtains to eliminate competing illumination.
Hold the flashlight at a low angle; the oblique beam highlights texture differences and shadows.
Scan mattress edges, box‑spring seams, headboard joints, and upholstered furniture stitching.
Inspect baseboard gaps, wall‑to‑floor transitions, and behind picture frames.
Look for live insects (approximately 5 mm, reddish‑brown), translucent nymphs, shed exoskeletons, or tiny dark spots (fecal stains).

A flashlight also helps confirm other indicators. Dark specks on sheets or walls suggest fecal deposits; tiny white eggs may appear near cracks. If you spot any of these signs, collect a specimen for laboratory verification.

Reliance on visual inspection alone has limits. Early infestations may involve few insects, making detection difficult even with strong light. Complement flashlight checks with mattress encasements, passive traps, or professional pest‑inspection services for comprehensive assessment.

Performing a Detailed Visual Check

A thorough visual inspection is the most reliable method for confirming the presence of bedbugs in a dwelling. Begin by removing bedding, curtains, and any fabric coverings from the mattress and box spring. Examine seams, folds, and stitching with a magnifying glass or strong light source. Look for live insects, which are reddish‑brown and about the size of an apple seed, as well as their shed skins, which appear as translucent, oval shells.

Next, focus on common harborages:

Headboard, especially seams and cracks.
Bed frame joints and wooden slats.
Upholstered furniture, paying attention to cushions, tufts, and underneath fabric.
Baseboards, wall outlets, and electrical switch plates.
Behind picture frames, wall hangings, and decorative items.

Finally, inspect the surrounding environment. Check floorboards, carpet edges, and any crevices in walls or flooring. Use a flashlight to illuminate dark corners and a disposable card or tape to collect suspected specimens for laboratory verification. Document findings with photographs and notes to support any subsequent pest‑control actions.

When to Seek Professional Help

Signs of a Widespread Problem

A large‑scale bedbug presence manifests through multiple, overlapping indicators throughout the living space.

Numerous bite marks on several occupants, often appearing in clusters on exposed skin.
Dark, rust‑colored spots on mattresses, box springs, and furniture; these are digested blood stains left by insects after feeding.
Small, translucent exuviae shed by growing nymphs, scattered across seams, folds, and crevices.
Live insects or fresh eggs discovered in various rooms, not confined to a single bedroom.
A sweet, musty odor detectable in closets, under furniture, or near baseboards, resulting from the bugs’ scent glands.
Heavy infestations produce a visible concentration of bugs in seams of upholstery, behind headboards, and within wall voids.
Infested fabrics show extensive staining or discoloration from repeated feeding events.

When these signs appear in several locations, the problem has likely spread beyond a localized pocket, demanding comprehensive treatment rather than spot remediation.

Difficulty in Self-Identification

Identifying a bed‑bug infestation without professional assistance is challenging because the insects are minute, hide in concealed locations, and resemble other common pests. Their nocturnal activity limits direct observation; most encounters occur after they have retreated to cracks, seams, or furniture interiors.

Key factors that impede accurate self‑diagnosis include:

Size and coloration: adult bugs measure 4–5 mm, a length comparable to a grain of rice, and their reddish‑brown hue is indistinguishable from many harmless arthropods.
Limited mobility: bed bugs remain motionless for extended periods, only emerging to feed, which reduces opportunities for visual confirmation.
Bite ambiguity: skin reactions vary widely; similar marks can result from mosquitoes, fleas, or allergic responses, making bite evidence unreliable.
Concealed habitats: infestations often develop behind headboards, within mattress seams, or in wall voids, areas most residents do not inspect regularly.
Population thresholds: early infestations involve few individuals, producing scant evidence such as isolated fecal spots or occasional shed skins.

Because these obstacles obscure definitive evidence, reliance on visual cues alone frequently leads to false negatives or misidentification. Professional inspection, which incorporates trained detection methods and specialized tools, remains the most reliable approach for confirming the presence of bed bugs.