Can bedbugs be eliminated with steam from a steam generator?

Understanding Bed Bugs

Biology and Behavior of Bed Bugs

Bed Bug Life Cycle

Bed bugs (Cimex lectularius) develop through a predictable series of stages that determine their vulnerability to control measures.

The life cycle begins when a female deposits 1–5 eggs per day on flat surfaces near a host’s sleeping area. Eggs are 0.5 mm in length, translucent, and hatch within 6–10 days at temperatures of 70–80 °F (21–27 °C).

After hatching, the emerging first‑instar nymph, often called a “crawler,” must obtain a blood meal to initiate molting. Bed bugs undergo five successive molts, each requiring a fresh feeding to progress to the next instar. The duration of each instar varies with temperature and food availability:

1st instar: 4–6 days post‑feeding at 80 °F (27 °C)
2nd instar: 5–7 days
3rd instar: 6–10 days
4th instar: 7–12 days
5th instar: 8–14 days

At each stage, the insect’s size increases from about 1.5 mm to 5 mm, and its blood‑feeding frequency typically ranges from every 3–5 days for early instars to weekly for mature adults.

Adult females live 6–12 months, producing 200–500 eggs over their lifespan. Reproduction ceases when temperatures drop below 50 °F (10 °C) or when hosts are absent for extended periods.

Critical thermal thresholds affect survival: exposure to temperatures above 122 °F (50 °C) for 30 seconds or to below 0 °F (‑18 °C) for 4 hours is lethal to all stages, including eggs. Moist heat applied directly to the insect’s body disrupts protein structures, leading to rapid mortality.

Understanding the timing of each developmental phase and the temperature limits that cause death is essential for evaluating any heat‑based eradication technique.

Common Hiding Places

Bedbugs reside in locations that protect them from disturbance and maintain proximity to a host. Their preference for tight, dark, and warm micro‑environments dictates the most effective points of contact for steam‑based control.

Mattress seams, tags, and tufts
Box‑spring folds and internal frames
Bed frame cracks, headboard joints, and footboard corners
Upholstered furniture cushions, springs, and stitching lines
Sofa and armchair crevices, especially under cushions and behind removable covers
Picture frames, wall hangings, and surrounding wall voids
Baseboard gaps and shoe‑rack slots
Electrical outlet covers, switch plates, and wiring channels
Carpet edges, under rugs, and floorboard seams
Luggage compartments, suitcase seams, and travel bags

Applying saturated steam at 100 °C (212 °F) directly to these sites penetrates the insects’ protective layers, causing rapid dehydration. Successful treatment requires thorough coverage, slow movement of the steam nozzle, and repeated passes to reach concealed pockets. Ignoring any of the listed locations reduces overall efficacy and permits reinfestation.

Signs of Infestation

Identifying a bed‑bug problem early prevents extensive infestation and guides effective steam‑based control.

Small, reddish‑brown insects about the size of an apple seed, often found in seams of mattresses, box‑spring frames, and headboards.
Dark‑red or rust‑colored spots on sheets and pillowcases, representing crushed bugs or digested blood.
Tiny, dark fecal specks on bedding, furniture, or walls, typically 1 mm in diameter.
Transparent exuviae (shed skins) near hiding places, indicating growth cycles.
Itching, red welts arranged in a line or cluster on exposed skin, especially after night‑time exposure.
A faint, sweet, musty odor detectable in heavily infested rooms.
Presence of eggs, about 1 mm long, attached to fabric folds or cracks.

Each indicator confirms activity and justifies the application of high‑temperature steam to eradicate the population.

Steam Treatment for Bed Bugs

How Steam Works Against Bed Bugs

The Principle of Heat Eradication

Heat eradication works by raising the temperature of an infested area above the thermal death point of the target organism. For bedbugs, mortality occurs when body temperature reaches approximately 45 °C (113 °F) for a sustained period. The relationship between temperature and exposure time is inverse: higher temperatures require shorter contact times, while lower temperatures need longer exposure.

Steam generators produce saturated vapor at temperatures typically ranging from 100 °C to 120 °C (212 °F–248 °F). When directed onto surfaces, the steam transfers heat rapidly through condensation, raising the temperature of the underlying material and any concealed insects. The effectiveness of this method depends on several factors:

Temperature of the steam: Must exceed the thermal death point to ensure lethal heat.
Contact duration: Minimum exposure of 90 seconds at 45 °C, or 30 seconds at 55 °C, is required for complete mortality.
Penetration depth: Steam can infiltrate cracks, seams, and fabric fibers, reaching insects hidden in shelters.
Moisture tolerance: Bedbugs can survive brief desiccation, but the combination of heat and moisture disrupts their physiological processes, leading to rapid death.

Practical application requires uniform coverage of all infested zones. Areas that receive insufficient steam may harbor survivors, allowing re‑infestation. To achieve comprehensive treatment, operators typically move the nozzle slowly, maintaining a consistent distance of 5–10 cm from surfaces, and repeat passes to eliminate thermal shadows.

In summary, the principle of heat eradication leverages the lethal temperature threshold of bedbugs, using high‑temperature steam to deliver rapid, penetrative heat that exceeds this threshold for a sufficient duration, resulting in total mortality when applied correctly.

Effective Temperature Ranges

Steam generated by a professional-grade unit can eradicate bedbugs when applied at temperatures that exceed the insects’ thermal tolerance. Scientific studies identify a minimum lethal temperature of 45 °C (113 °F) provided the exposure lasts at least five minutes. However, field conditions rarely allow continuous contact for that duration, so higher temperatures are recommended to ensure rapid mortality.

48 °C–50 °C (118 °F–122 °F): Effective with 2–3 minutes of direct steam contact. Suitable for exposed surfaces such as mattress seams, baseboards, and furniture frames.
55 °C–60 °C (131 °F–140 °F): Guarantees kill within 30–60 seconds. Ideal for dense fabrics, upholstery, and cracks where steam penetration is limited.
Above 70 °C (158 °F): Immediate lethality within seconds. Used for stubborn infestations in crevices, electrical outlets, and carpet edges, but requires careful handling to avoid material damage.

Steam generators must maintain consistent output above the selected temperature range throughout the treatment. Thermocouples or built‑in temperature gauges verify that the steam remains within the target band. Insufficient temperature or premature cooling reduces efficacy and may allow survivors to repopulate.

Materials sensitive to heat—such as certain plastics, delicate electronics, or thin silk—should be protected or treated with alternative methods to prevent damage while still achieving pest control.

Equipment and Techniques for Steam Treatment

Types of Steam Generators

Steam generators differ in design, temperature range, and intended use, influencing their effectiveness against bedbugs.

Portable handheld units produce steam at 120–150 °C, powered by electric heating elements. Their compact size permits direct treatment of mattresses, furniture seams, and crevices where insects hide. Rapid heat delivery and quick cooldown reduce the risk of surface damage but limit sustained exposure time.

Professional-grade models feature larger water reservoirs and thermostatically controlled boilers that maintain temperatures of 165–210 °C. These machines deliver continuous high‑temperature steam for extended periods, allowing thorough coverage of entire rooms or large furnishings. Heavy-duty construction often includes insulated hoses and adjustable nozzles for precise targeting.

Industrial steam generators operate with pressurized boilers, achieving temperatures above 210 °C and flow rates exceeding 5 L/min. Designed for large‑scale pest‑control operations, they can treat whole dwellings or commercial spaces in a single pass. Integration with vacuum extraction systems removes dislodged insects and debris, enhancing overall eradication efficiency.

Key characteristics to consider when selecting a generator for bedbug control:

Temperature stability: consistent heat above the lethal threshold for all life stages.
Steam output: sufficient volume to saturate deep cracks and fabric layers.
Mobility: ease of transport and maneuverability within confined spaces.
Safety features: automatic shut‑off, insulated handles, and pressure relief valves.

Understanding these categories enables informed decisions about which steam equipment best matches the scale and severity of an infestation.

Proper Application Methods

Steam treatment can reach the temperatures required to kill bedbug eggs, nymphs, and adults when applied correctly. The effectiveness depends on temperature, exposure time, and thorough coverage of hiding places.

Heat the generator until the nozzle consistently emits steam at 212 °F (100 °C) or higher.
Direct the steam jet at seams, mattress edges, box‑spring folds, and furniture joints; maintain a distance of 1–2 inches to ensure contact without cooling.
Move the nozzle slowly, holding each spot for at least 10 seconds to allow heat penetration.
Overlap each pass by 20–30 % to avoid untreated gaps.
After steaming, allow the treated area to dry completely; residual moisture can attract mold.

Additional precautions:

Wear heat‑resistant gloves and eye protection to prevent burns.
Ensure adequate ventilation to disperse steam and reduce humidity.
Test the steam temperature on a hidden fabric patch before full‑scale application to verify material tolerance.
Repeat the process after 7–10 days to target any newly hatched insects that survived the initial exposure.

Following these procedures maximizes the likelihood of eradicating bedbugs with a steam generator.

Safety Precautions

When employing a steam generator to eradicate bedbugs, strict safety measures are essential to protect occupants and preserve property.

Operators must wear heat‑resistant gloves, eye protection, and long‑sleeved clothing to prevent burns from high‑temperature steam. Footwear with slip‑resistant soles reduces the risk of falls on wet surfaces.

Electrical safety requires inspecting cords for damage, using grounded outlets, and avoiding water contact with plugs or switches. Portable generators should be placed on stable, non‑flammable surfaces away from the treatment area.

Steam temperatures typically exceed 120 °C (250 °F); prolonged exposure can damage fabrics, wood finishes, and electronic devices. Test a small, inconspicuous area before full application, and keep steam no closer than 2 inches to delicate materials.

Fire hazards arise from igniting flammable substances. Remove or cover curtains, bedding, and upholstery that may catch fire. Ensure the room is free of open flames, cigarettes, and combustible liquids.

Ventilation mitigates the buildup of humidity, which can promote mold growth. Open windows or use dehumidifiers after treatment to restore normal moisture levels.

Children, pets, and individuals with respiratory conditions must be evacuated from the treated space until it has cooled and dried completely.

Key precautions

Wear protective gloves, goggles, and long sleeves.
Verify electrical equipment integrity and grounding.
Conduct a material compatibility test before full exposure.
Keep steam distance at least 2 inches from vulnerable surfaces.
Eliminate flammable items and sources of ignition.
Provide adequate ventilation and post‑treatment drying.
Exclude vulnerable occupants until the environment is safe.

Efficacy and Limitations of Steam Treatment

Advantages of Using Steam

Non-Toxic and Chemical-Free

Steam generated by a portable vaporizer offers a non‑toxic, chemical‑free method for eliminating bedbugs. The approach relies on delivering saturated heat directly to insects and their eggs, causing immediate protein denaturation and desiccation.

Effective treatment requires temperatures of at least 120 °F (49 °C) sustained for 30 seconds on each surface. Lower temperatures may incapacitate adult bugs but leave eggs viable. Consistent contact is essential; steam must penetrate cracks, seams, and fabric folds where pests hide.

Advantages of a heat‑only protocol:

No residues that could affect occupants, pets, or indoor air quality.
No risk of chemical resistance development in bedbug populations.
Immediate reduction of infestation visible after a single pass.
Compatibility with most household materials when temperature limits are observed.

Limitations include:

Requirement for thorough, methodical coverage; missed spots can sustain an infestation.
Potential damage to heat‑sensitive items such as certain plastics, adhesives, or delicate textiles.
Necessity for a reliable power source and adequate water supply during treatment.

When applied correctly, steam eradication matches or exceeds the efficacy of conventional insecticides while eliminating the hazards associated with toxic chemicals. For persistent problems, combine steam treatment with mechanical methods—vacuuming, laundering, and encasements—to ensure complete removal of all life stages.

Reaching Hidden Areas

Effective eradication of bedbugs using steam requires precise delivery of heat into concealed habitats such as mattress seams, wall voids, and furniture joints. Steam generators produce saturated vapor at temperatures of 100 °C (212 °F) or higher, allowing heat to travel through narrow openings that chemical sprays cannot reach.

The high temperature of steam collapses the exoskeleton of bedbugs and destroys their eggs within seconds of contact. Penetration depth depends on steam pressure, nozzle design, and the size of the gap. A narrow‑tip nozzle concentrates vapor, forcing it into cracks as small as 1 mm, while a wide‑angle nozzle disperses heat over broader surfaces.

Key practices for accessing hidden zones:

Use a portable, high‑pressure unit capable of maintaining continuous steam flow for at least 30 seconds per spot.
Attach a flexible hose with a detachable nozzle to reach under bed frames, into closet rods, and behind baseboards.
Apply steam slowly, moving the nozzle along seams and edges to ensure complete coverage.
Pause briefly after each pass to allow the material to absorb heat, preventing rapid cooling that could allow survivors.

Materials sensitive to high heat—such as delicate fabrics, electronics, or painted surfaces—must be protected with heat‑resistant barriers or avoided entirely. Void spaces that lack direct line‑of‑sight may require drilling small pilot holes to introduce steam, followed by sealing to maintain treatment efficacy.

When executed with proper equipment and technique, steam can infiltrate the concealed environments where bedbugs hide, delivering lethal temperatures that chemical methods often miss. The method offers a rapid, residue‑free alternative for comprehensive pest control.

Immediate Kill Rate

Steam applied at temperatures of 120 °C (248 °F) or higher kills adult bedbugs, nymphs, and eggs within seconds. The immediate kill rate depends on three variables: temperature, exposure duration, and contact quality. When the steam jet contacts the insect’s exoskeleton, heat denatures proteins and ruptures cellular membranes, resulting in rapid mortality.

Temperature: 120 °C achieves >95 % mortality in under 5 seconds; 140 °C reaches >99 % in 2–3 seconds.
Exposure time: Direct contact for 5 seconds eliminates >99 % of life stages; indirect exposure (ambient heat) requires at least 30 seconds.
Contact quality: Full coverage of the body surface, including hidden crevices, maximizes kill rate; partial coverage reduces effectiveness proportionally.

Laboratory studies confirm that a portable steam generator producing saturated steam at 130 °C eliminates bedbugs instantly when the nozzle is held within 2 cm of the target for 4 seconds. Field trials report comparable results on mattresses, furniture seams, and wall voids, provided the operator maintains continuous steam flow and avoids cooling of the jet. Consequently, immediate kill rates are consistently high when proper technique and sufficient temperature are ensured.

Disadvantages and Challenges

Time-Consuming Process

Steam treatment is a physical method that requires extensive time investment to achieve reliable bed‑bug control. The process begins with thorough room preparation: all clothing, linens, and removable items must be laundered or sealed, and clutter cleared to allow unobstructed steam penetration. This stage alone can occupy several hours in a typical bedroom.

Application of steam demands precise technique. A generator must be heated to at least 150 °C, a step that takes 10–15 minutes. The nozzle must be moved slowly, maintaining a 1‑inch distance from surfaces, to ensure the lethal temperature reaches insects hidden in cracks, seams, and fabric folds. Each pass over a surface requires 2–3 seconds of contact; complete coverage of a standard mattress, for example, demands 30–40 passes, translating to 5–7 minutes of active steaming.

After the initial pass, residual heat dissipates within 5–10 minutes, but surviving eggs may hatch later, necessitating repeated cycles. Professional guidelines recommend at least three treatment sessions spaced 5–7 days apart, extending the overall timeline to two weeks or more when accounting for scheduling and access constraints.

Additional time factors include:

Drying of treated fabrics (30–60 minutes)
Re‑inspection and spot‑treatment of missed areas (15–20 minutes per session)
Equipment cooldown and maintenance (10 minutes)

Collectively, these steps make steam‑based eradication a labor‑intensive approach, unsuitable for rapid resolution but effective when sufficient time is allocated.

Potential for Missed Bed Bugs

Steam treatment can reach temperatures that kill bed bugs on exposed surfaces, but the method does not guarantee complete eradication. Adult insects, nymphs, and eggs often hide in locations that steam cannot penetrate, such as deep within mattress seams, behind wall panels, or inside tightly packed furniture crevices. When the steam jet contacts a surface for only a few seconds, the heat may not sustain the lethal threshold long enough to affect hidden stages.

Key factors that increase the risk of overlooking insects include:

Insufficient exposure time – brief contact fails to maintain temperatures above 120 °F (49 °C) for the required duration.
Limited reach – steam nozzles cannot access narrow gaps, voids, or sealed encasements.
Egg resilience – some eggs survive brief heat spikes, especially when insulated by debris.
Operator error – uneven sweeping patterns or low-pressure settings leave patches untreated.

Even when visible bugs are eliminated, residual populations can repopulate the area within days. Combining steam with complementary measures—such as vacuuming, encasements, and professional pesticide application—reduces the likelihood that any insects remain undetected.

Reinfestation Risks

Steam treatment can achieve high mortality among adult bedbugs and nymphs, yet several factors sustain the threat of subsequent infestations. Surviving eggs, which resist temperatures below 120 °F (49 °C), may hatch after the heat exposure ends, reestablishing a population. Incomplete penetration of steam into cracks, crevices, and deep mattress folds leaves protected refuges where insects persist. Mechanical limitations of handheld generators often result in uneven temperature distribution, creating thermal “cold spots” that fail to reach lethal thresholds.

Key reinfestation drivers include:

Residual eggs that escape heat exposure
Hidden harborages not reached by the steam nozzle
Reintroduction via travelers, used furniture, or pets
Inadequate treatment cycles that omit repeat applications
Failure to integrate chemical controls or monitoring devices

Mitigation requires multiple steam passes, verification of temperature at target sites, and complementary strategies such as encasements, vacuuming, and regular inspections. Without these safeguards, the initial reduction in bedbug numbers may be temporary, and a resurgence can occur within weeks.

Integrated Pest Management for Bed Bugs

Combining Steam with Other Methods

Vacuuming and Laundry

Vacuuming removes adult insects, nymphs, and eggs from surfaces where steam may not reach. Use a high‑efficiency vacuum equipped with a sealed bag or disposable canister; discard the contents immediately in an outdoor trash container. After each session, clean the filter and hose with hot, soapy water to prevent re‑infestation.

Laundry eliminates hidden stages of the pest that reside in clothing, bedding, and fabric accessories. Follow these procedures:

Separate infested items from uncontaminated laundry.
Wash at a minimum temperature of 60 °C (140 °F) for at least 30 minutes; higher temperatures increase mortality.
Dry on high heat for a minimum of 20 minutes, ensuring the dryer reaches at least 65 °C (149 °F).
Seal cleaned items in airtight bags until the surrounding environment has been treated with steam.

Combining thorough vacuuming with high‑temperature washing and drying reduces the overall population and prevents survivors from re‑establishing after steam application. Regular repetition of both actions, especially after steaming, sustains control and minimizes the risk of resurgence.

Encasements and Traps

Encasements provide a physical barrier that isolates insects from their host and prevents them from laying eggs in mattresses, box springs, and pillows. High‑denier fabrics with sealed seams block both adult bedbugs and newly hatched nymphs, forcing any existing population to seek alternative harborage. When steam treatment is applied, the heat penetrates the fabric but does not compromise the barrier, allowing the encasement to remain effective after the session.

Traps complement barrier methods by capturing insects that migrate away from treated zones. Common designs include:

Interceptor cups placed under each leg of the bed frame; a smooth inner surface directs bugs into a containment chamber.
Sticky pads positioned near seams, cracks, or furniture edges; adhesive surfaces retain insects that contact them.
Pheromone‑baited traps that lure bedbugs from hiding places; the attractant increases capture rates during and after steam exposure.

Using encasements and traps alongside steam creates a multi‑layered approach: steam reduces the existing population, encasements prevent re‑infestation, and traps monitor residual activity. Regular inspection of traps informs the need for additional steam cycles or replacement of compromised encasements.

Chemical Treatments

Chemical treatments remain the primary method for controlling bedbug infestations. Insecticides are formulated to target the nervous system of the insects, causing rapid paralysis and death. Common classes include pyrethroids, neonicotinoids, and desiccant powders such as diatomaceous earth. Each class operates differently:

Pyrethroids: synthetic analogs of natural pyrethrins; degrade quickly under sunlight but retain potency on indoor surfaces.
Neonicotinoids: bind to nicotinic acetylcholine receptors; effective against resistant populations when applied at label rates.
Desiccant powders: abrade the waxy cuticle, leading to dehydration; require thorough coverage of hiding spots.

Application methods vary: spray formulations cover cracks, crevices, and mattress seams; dusts are dusted into voids; foggers disperse aerosol particles throughout rooms. Proper dosing, thorough coverage, and repeat treatments at 7‑ to 10‑day intervals align with the bedbug life cycle and improve eradication success.

Chemical approaches complement thermal methods. Steam can kill insects on contact but fails to reach protected areas such as deep fabric folds or wall voids. Residual insecticides maintain activity after steam treatment, addressing re-infestation risk. Integrated pest management protocols typically combine high‑temperature exposure with targeted chemical applications to achieve comprehensive control.

Prevention and Monitoring

Regular Inspections

Regular inspections form the backbone of any steam‑based bedbug management program. Detecting infestations early limits the number of treatment cycles required and prevents spread to adjacent areas.

Inspection should occur before the first steam application, after each treatment session, and at scheduled intervals thereafter. Recommended frequency includes:

Initial assessment: thorough visual examination of mattresses, box springs, headboards, seams, and furniture crevices.
Post‑treatment check: within 24‑48 hours to confirm mortality signs such as darkened exoskeletons and absence of movement.
Ongoing monitoring: weekly for the first month, then bi‑weekly for the next two months, and monthly thereafter if no new activity appears.

Inspectors must use a high‑intensity flashlight and a magnifying lens to spot live insects, eggs, and shed skins. Areas that retain moisture or have high humidity merit extra scrutiny, as they may shelter surviving bugs that evade steam exposure.

Documenting findings in a standardized log—recording date, location, life‑stage observed, and treatment response—provides data for evaluating efficacy and adjusting steam parameters. Consistent records also support decision‑making when determining whether additional steam cycles, chemical adjuncts, or professional intervention are necessary.

By maintaining a disciplined inspection schedule, operators ensure that steam treatment remains effective, reduces the risk of re‑infestation, and delivers measurable results.

Sealing Cracks and Crevices

Sealing cracks and crevices is a critical component of any strategy that relies on steam treatment to control bedbug populations. Steam can penetrate porous surfaces, but gaps larger than a few millimeters allow insects to escape the thermal exposure required for mortality. By eliminating these escape routes, the effectiveness of the steam application increases dramatically.

Proper sealing involves the following actions:

Identify all openings in walls, baseboards, flooring seams, and furniture joints using a bright flashlight or a thin probe.
Clean each opening to remove dust, debris, and residual insect residues that could impede adhesive bonding.
Apply a high‑temperature‑resistant caulk or sealant that remains stable under steam temperatures of 150–180 °C (300–350 °F). Silicone‑based or polyurethane sealants designed for heat‑exposed environments are suitable.
Smooth the sealant to ensure complete coverage, eliminating any air pockets that could harbor insects.
Allow the sealant to cure according to the manufacturer’s specifications before re‑exposing the area to steam.

In addition to structural sealing, consider the following preventive measures:

Install weatherstripping on doors and windows to block external entry points.
Use fabric‑tightened covers for mattress seams and pillowcases to reduce hidden niches.
Regularly inspect and reseal any areas where movement or wear may have compromised the original seal.

By integrating thorough sealing with targeted steam application, the likelihood of bedbug survival is reduced, and the overall treatment outcome becomes more reliable.

Travel Precautions

Travelers facing the risk of bed‑bug infestations should adopt measures that limit exposure and facilitate elimination if an infestation occurs. Portable steam generators produce temperatures above 120 °C, sufficient to kill bed‑bug eggs and adults when applied directly to mattresses, furniture seams, luggage straps, and upholstery. Steam treatment must reach all hidden crevices; incomplete coverage leaves viable insects.

Before departure, inspect hotel rooms for signs of infestation: shed skins, tiny dark spots, or live insects along headboards, mattress seams, and wall outlets. Use a flashlight to examine these areas. If evidence appears, request a room change or relocate to a property with documented pest‑control practices.

During the stay, keep clothing and luggage off beds and upholstered surfaces. Store garments in sealed plastic bags; consider using luggage encasements designed to prevent insect entry. Upon returning home, isolate luggage in a garage or utility room, then apply steam to external surfaces, focusing on zippers, handles, and fabric folds. Follow the manufacturer’s guidelines for dwell time to ensure lethal temperatures penetrate material layers.

A concise checklist for post‑travel decontamination:

Unpack in a well‑ventilated area; discard or wash all fabrics on the hottest cycle compatible with the material.
Vacuum suitcases, backpacks, and travel accessories, then empty the vacuum canister into an outdoor trash bin.
Run a steam device over suitcase seams, pockets, and strap buckles for at least 30 seconds per spot.
Store cleaned luggage in a sealed container until the next trip.

Adhering to these precautions reduces the probability of transporting bed‑bugs and maximizes the effectiveness of steam‑based eradication when it is employed.