When do fleas die after being treated with spot‑on drops on the neck?

Understanding Spot-On Flea Treatments

How Spot-Ons Work

Active Ingredients and Their Mechanisms

Spot‑on treatments applied to the neck deliver a precise dose of insecticide that spreads across the skin’s oil layer, reaching parasites on the body.

The most common actives are:

Fipronil – blocks GABA‑gated chloride channels, causing uncontrolled neuronal firing and rapid paralysis. Fleas typically cease moving within 4–8 hours, death follows shortly thereafter.
Imidacloprid – acts as a nicotinic acetylcholine receptor agonist, overstimulating nerve signals and inducing paralysis. Knock‑down occurs in 2–6 hours; mortality is usually complete by 12 hours.
Selamectin – binds glutamate‑gated chloride channels, increasing chloride influx and hyper‑polarizing nerve cells. Fleas become immobile within 6 hours, with full death by 24 hours.
Fluralaner (and related isoxazolines) – inhibits GABA and glutamate receptors simultaneously, producing sustained neurotoxicity. Flea kill time averages 8–12 hours, extending up to 24 hours for resistant populations.

All ingredients are lipophilic, allowing rapid diffusion through the dermal surface and into the flea’s cuticle. The systemic spread ensures exposure of fleas feeding on the host’s blood or walking on the coat, leading to swift lethal action without requiring multiple applications.

Absorption and Distribution in the Pet's System

Topical flea medication applied to the neck is absorbed through the skin and enters the bloodstream within minutes. The active ingredients bind to plasma proteins and are carried to the skin surface via the circulatory system. Distribution follows the animal’s peripheral circulation, reaching the epidermis and hair follicles where adult fleas and larvae feed.

The pharmacokinetic profile determines how quickly fleas are affected:

Absorption phase: 5–30 minutes after application, systemic levels rise sharply.
Peak concentration: 2–4 hours, sufficient to kill newly attached adult fleas.
Sustained activity: 24 hours onward, maintaining lethal exposure for fleas that bite later.

Fleas die because the insecticide interferes with nervous signaling, causing paralysis and death. Most adult fleas encountered within the first 12 hours are eliminated, and any that attach later are affected as the drug persists in the skin for up to a month.

Flea Life Cycle and Treatment Efficacy

Stages of the Flea Life Cycle

Eggs

Flea eggs are laid on the host’s skin or in the environment within 24 hours after a female begins feeding. Spot‑on treatments applied to the neck release insecticide that spreads over the animal’s body and contaminates the surrounding area. The chemicals act primarily on adult fleas, but they also affect developing eggs that come into contact with treated fur or skin.

Eggs that fall onto the treated coat are exposed to the insecticide within minutes; most die before hatching.
Eggs already in the environment survive until the insecticide is transferred to the bedding, typically within 12–24 hours.
Unhatched eggs lose viability after 48 hours of continuous exposure to the residual activity of the product.

Consequently, the majority of flea eggs become non‑viable within two days of the initial application, while any remaining eggs are eliminated as the treatment’s residual effect persists for several weeks. Effective control therefore requires both the immediate kill of adult fleas and the rapid neutralization of eggs to break the life cycle.

Larvae

Spot‑on flea products are applied to the animal’s nape, where they disperse through skin oils and coat the surrounding environment. The active chemicals affect both adult fleas and the immature stages that develop in the pet’s bedding and carpet.

Flea larvae do not feed on the host; they consume organic debris and adult flea feces that contain the insecticide. Once the treated animal sheds skin oils, the insecticide contaminates the litter where larvae reside, interrupting their growth and causing death.

Typical mortality timeline after a single application:

Adult fleas: 4–6 hours for most products.
Newly hatched larvae: 12–24 hours after exposure to contaminated debris.
Older larvae (second‑instar and beyond): 24–48 hours, depending on concentration and environmental humidity.

Factors that modify larval kill rate include:

Correct dosage relative to animal weight.
Frequency of cleaning; removal of heavily contaminated material can reduce exposure.
Ambient temperature; higher temperatures accelerate larval metabolism and increase susceptibility.

Effective control relies on eliminating the adult population while simultaneously exposing developing larvae to the insecticide, ensuring the entire life cycle is disrupted within two days of treatment.

Pupae

Spot‑on flea treatments applied to the neck area act systemically; the active ingredient circulates in the animal’s bloodstream and reaches the skin surface where adult fleas feed. Adult fleas die within a few hours after contact with the toxic dose, typically 4–6 hours. The pupal stage, however, remains protected inside its cocoon until a host’s movement or heat triggers emergence. Because the pupae are not feeding, they are not directly exposed to the medication while enclosed.

The following timeline reflects the expected outcome for pupae after a single application of a standard spot‑on product:

0–24 hours: No effect on pupae; cocoons stay intact, awaiting emergence cues.
24–48 hours: Emerging adults encounter treated skin, die rapidly; no new pupae are produced.
48–72 hours: Most remaining cocoons either rupture without producing viable adults or release adults that die on contact with the host.
72 hours onward: The flea population on the animal is typically eliminated; any surviving pupae will eventually die from lack of a host or environmental exposure.

Consequently, while adult fleas succumb quickly, pupae require up to three days to be eliminated indirectly through the death of emerging adults and the absence of a viable host. Re‑treatment may be advised if environmental infestation persists.

Adult Fleas

Adult fleas exposed to a spot‑on treatment applied to the neck typically die within a predictable time frame. The active ingredients—often a combination of insect growth regulators and neurotoxic agents—begin to affect the flea’s nervous system almost immediately after contact. Most adult fleas stop feeding within 30 minutes and become immobilized within 2–4 hours. Complete mortality usually occurs between 12 and 24 hours, depending on the product concentration and the flea’s resistance level.

Key factors influencing the death timeline:

Product formulation: Products containing fipronil or imidacloprid act faster than those relying primarily on insect growth regulators.
Flea load: Higher infestations may extend the period to full kill by a few hours.
Environmental temperature: Warm conditions accelerate metabolic processes, shortening the interval to death.

Veterinary guidelines recommend re‑checking the animal after 24 hours to confirm the absence of live adult fleas. If any are observed beyond this window, a second treatment or alternative product may be necessary.

Impact of Spot-Ons on Different Life Stages

Adult Fleas

Adult fleas are wingless insects that feed exclusively on blood. They locate a host by detecting heat, carbon‑dioxide, and movement, then attach to the skin and begin rapid blood meals. A single adult can ingest several milliliters of blood per day and lay up to 50 eggs, sustaining an infestation if not interrupted.

Spot‑on treatments applied to the neck region contain neurotoxic compounds such as imidacloprid, fipronil, or selamectin. These chemicals disperse through the animal’s sebaceous secretions, coating the fur and skin. When a flea contacts the treated surface, the toxin interferes with nerve transmission, causing paralysis and death.

Typical mortality timeline after a correct application:

12 hours: early signs of paralysis in a minority of fleas.
24 hours: most adult fleas exhibit loss of mobility.
48 hours: near‑complete eradication of adult fleas on the host.

The exact speed varies with:

Active ingredient and concentration.
Size and coat thickness of the animal.
Grooming behavior that may redistribute the product.
Presence of resistant flea strains.
Ambient temperature, which influences toxin absorption.

Effective control requires a single dose that eliminates the adult stage on the pet, followed by environmental measures (vacuuming, washing bedding, insecticidal sprays) to address eggs, larvae, and pupae that emerge after the adult population is removed. Re‑application according to the product label sustains protection and prevents re‑infestation.

Immature Stages in the Environment

Spot‑on treatments applied to the neck region act rapidly on adult fleas that crawl onto the animal’s coat. Most products contain insecticides that begin to incapacitate adults within a few hours, with complete mortality typically observed by six hours after contact. The immediate loss of feeding adults prevents further deposition of eggs on the host.

Eggs laid before treatment remain in the environment for one to five days before hatching. Because the spot‑on does not directly affect eggs, their survival depends on the presence of viable adults to continue the life cycle. Once eggs hatch, larvae feed on organic debris and adult flea feces. Larval development usually requires five to ten days, after which the immature form spins a cocoon and enters the pupal stage. Pupae may remain dormant for several weeks, emerging only when environmental cues indicate a suitable host.

The primary impact of the neck‑applied product on immature stages is indirect:

Adult death eliminates new egg deposition, reducing the influx of eggs into the environment.
Decreased adult activity lowers the amount of flea feces, which serves as a critical food source for larvae.
Some larvae that wander onto the treated animal’s fur may be exposed to residual insecticide, leading to occasional mortality, though this effect is modest compared with adult kill rates.

Effective control of the immature population therefore requires complementary measures such as regular vacuuming, washing bedding, and, if necessary, environmental insecticide sprays. These actions remove eggs and larvae, shorten the development window, and prevent pupae from completing the cycle. When combined with the rapid adult kill provided by the spot‑on, the overall flea burden can be reduced dramatically within two to three weeks.

Timeline of Flea Mortality After Spot-On Application

Initial Hours: Rapid Knockdown Effect

Paralysis and Death of Existing Fleas

Spot‑on flea treatments are applied to the animal’s nape, where the active ingredient disperses through skin oils and reaches the circulatory system. The compound interferes with the flea’s nervous system, blocking GABA‑gated chloride channels or binding nicotinic acetylcholine receptors, which results in loss of motor control.

Paralysis of existing fleas begins shortly after the insect contacts the treated surface. Typical progression:

Within 5‑15 minutes: tremors and uncoordinated movement appear.
15‑30 minutes: complete loss of ability to walk or jump.
30‑60 minutes: most fleas cease all activity and become immobile.
1‑4 hours: the majority of affected fleas die; a small fraction may persist up to 24 hours, depending on species tolerance and product concentration.

The exact timing varies with the specific active ingredient, dosage, environmental temperature, and the number of fleas present. Faster paralysis and death are observed with higher‑potency formulations and warmer conditions, while heavy infestations can extend the overall clearance period.

Within 24-48 Hours: Peak Efficacy

Elimination of Most Adult Fleas on the Pet

Spot‑on flea treatments applied to the neck region begin killing adult fleas within minutes. The majority of adult insects die by the end of the first 12‑hour period, and virtually all are eliminated within 24 hours. The product’s active ingredients disperse through the animal’s skin oils, reaching the bloodstream and affecting fleas that bite.

0–30 minutes: initial contact kills a small fraction of fleas feeding at the time of application.
1–4 hours: rapid decline in live adult fleas; most are incapacitated.
4–12 hours: continued mortality; the population on the pet drops to negligible levels.
12–24 hours: near‑complete eradication of adult fleas on the host.

Residual activity of the spot‑on formulation protects the pet for several weeks, preventing new adult fleas from establishing a viable infestation. Effective elimination depends on correct dosing, proper application to the skin, and adherence to the product’s re‑treatment schedule.

Beyond 48 Hours: Residual Protection

Continued Protection Against New Infestations

Spot‑on treatments applied to the neck region begin killing adult fleas within four to six hours; most adults are eliminated by the end of the first day. Eggs and immature stages are disrupted by the insecticide’s residual activity, typically achieving complete control within 24 hours.

Maintaining protection against reinfestation relies on three core actions:

Environmental sanitation: Vacuum carpets, upholstery, and pet bedding daily; discard the vacuum bag or clean the canister after each use. Wash all washable fabrics in hot water (≥ 60 °C) and dry on high heat.
Preventive dosing schedule: Administer the next dose according to the product’s labeled interval, usually every 30 days, to sustain plasma levels that kill newly acquired fleas before they reproduce.
Barrier treatments: Apply an insect growth regulator (IGR) to the home’s perimeter or use a room spray that targets larvae and eggs, reducing the reservoir of emerging pests.

Regular inspection of the pet’s coat and skin confirms treatment efficacy; any live fleas observed after 24 hours warrant immediate veterinary consultation. Combining consistent dosing with rigorous environmental control prevents the establishment of a secondary infestation cycle.

Breaking the Flea Life Cycle

Spot‑on treatments applied to the nape of a pet deliver insecticide through the skin into the bloodstream. Adult fleas feeding on the host ingest the chemical within minutes, causing paralysis and death typically within 4–6 hours. Eggs already laid on the animal’s fur are not directly affected; they require contact with the insecticide after they fall off and land on treated skin or bedding. Larvae that encounter contaminated debris die as they develop, usually before reaching the pupal stage.

Key points in the disruption of the flea life cycle:

Adult mortality: 4–6 hours after exposure to the topical agent.
Egg viability: Reduced when fallen onto treated surfaces; hatch rate drops sharply within 24 hours.
Larval development: Ingested residues cause lethal effects; most larvae perish before pupation, often within 48 hours.
Pupal emergence: A significant portion of pupae fail to mature because the surrounding environment remains contaminated for up to 30 days, preventing re‑infestation.

Consequently, a single application interrupts the cycle at multiple stages, leading to a rapid decline in the flea population on the animal and in its environment. Re‑treatment intervals are designed to maintain residual activity throughout the flea’s 2‑month reproductive window, ensuring continued suppression of emerging adults.

Factors Influencing Flea Mortality Rate

Type of Spot-On Product

Different Active Ingredients and Their Potency

Spot‑on flea products rely on a limited set of insecticidal agents, each with distinct speed of action and residual effect. The principal compounds include:

Fipronil – disrupts GABA‑gated chloride channels, causing rapid paralysis. Flea death typically occurs within 2–4 hours after a single dose applied to the dorsal neck region; efficacy persists for up to 30 days.
Imidacloprid – binds to nicotinic acetylcholine receptors, leading to neural overstimulation. Mortality is observed in 4–8 hours, with a protective window of roughly 4 weeks.
Selamectin – interferes with glutamate‑gated chloride channels. Fleas usually perish within 6–12 hours; the product remains active for about 30 days.
Nitenpyram – a fast‑acting neonicotinoid that induces rapid paralysis. Flea kill time averages 30 minutes to 2 hours, but the effect lasts only 24 hours, making it suitable for immediate relief rather than long‑term control.
Spinosad – activates nicotinic acetylcholine receptors and blocks GABA receptors. Fleas die in 4–6 hours; residual activity extends to 30 days.

Potency correlates with both the molecular target and the formulation’s ability to spread across the animal’s skin. Compounds that act on multiple neural pathways (e.g., fipronil combined with (S)-methoprene) often achieve faster kill rates and longer protection. Conversely, agents designed for rapid knock‑down (such as nitenpyram) provide swift relief but require frequent re‑application for sustained control. Understanding these differences enables selection of a product that matches the desired speed of flea elimination and duration of protection.

Severity of Flea Infestation

Heavy vs. Light Infestations

Spot‑on applications applied to the neck deliver a rapid dose of insecticide that kills adult fleas on contact. In a low‑level infestation, most fleas are eliminated within 4–6 hours, with complete eradication typically observed by 12 hours. The limited number of parasites allows the chemical to reach lethal concentrations quickly throughout the host’s coat and skin.

In a high‑level infestation, the same treatment encounters a larger population of fleas and may also be challenged by immature stages (eggs, larvae) present in the environment. Initial mortality occurs within the same 4–6 hour window, but residual survivors can persist for 24–48 hours. Re‑treatment or supplemental environmental control is often required to achieve full clearance.

Key differences:

Onset of death – identical (≈4 hours) for both infestation levels.
Time to total elimination – light: ≤12 hours; heavy: 24–48 hours, sometimes longer.
Need for follow‑up – light: usually none; heavy: additional doses or environmental measures recommended.

Understanding these timelines helps pet owners set realistic expectations and plan complementary actions when dealing with varying flea burdens.

Pet's Individual Factors

Coat Type and Condition

The effectiveness of a spot‑on flea treatment applied to the neck is directly affected by the animal’s coat characteristics. A dense or double coat can slow the diffusion of the active ingredient through the skin, extending the period before fleas are eliminated. Conversely, a short, single‑layer coat permits rapid spread, allowing fleas to die within the typical 4–6‑hour window.

Coat condition also influences the timeline:

Dry, well‑conditioned fur – minimal barrier to absorption; flea mortality usually observed in 4–8 hours.
Oily or heavily conditioned fur – oil residues can dilute the medication; flea death may be delayed to 8–12 hours.
Wet or damp coat – water can interfere with the product’s adhesion; fleas often survive up to 12–24 hours before succumbing.
Matted or tangled fur – uneven distribution of the drop; some fleas may persist for 24 hours or longer.

Pets with extremely thick or heavily matted coats may require a second application or supplemental treatment to achieve complete eradication within the expected timeframe. Regular grooming before applying spot‑on drops maximizes contact with the skin, ensuring the active ingredient reaches the bloodstream promptly and reduces the survival period of fleas.

Bathing Habits and Water Exposure

Bathing a dog shortly after applying a spot‑on flea medication can dilute or wash away the active ingredients, potentially delaying the lethal effect on fleas. Most spot‑on products are formulated to spread across the skin within a few hours; if the animal is bathed before this process completes, the concentration that reaches the parasites may be reduced.

The typical waiting period before the first bath ranges from 24 to 48 hours, depending on the specific formulation. During this interval, the medication adheres to the hair shaft and skin, establishing a reservoir that continues to release the insecticide. Once the reservoir is in place, fleas usually begin to die within 4–8 hours, with the majority eliminated by 24 hours.

Key considerations for water exposure:

Avoid submerging the animal in water or applying shampoo within the first two days after treatment.
Rinse only with a damp cloth if immediate cleaning is necessary; do not use high‑pressure streams.
After the initial waiting period, normal bathing practices do not interfere with the efficacy of the spot‑on product.

If a bath occurs earlier than recommended, re‑application of the medication may be required to restore the intended flea‑killing timeline. Monitoring the pet for signs of flea activity after the prescribed waiting period helps confirm that the treatment remains effective.

Environmental Conditions

Household Flea Burden

Spot‑on treatments applied to the nape of the animal act systemically; the active ingredients circulate in the bloodstream and reach fleas that bite the host. Within 24 hours, most adult fleas feeding on the treated animal are killed, sharply reducing the household infestation. Eggs and larvae already present in the environment survive longer because they are not directly exposed to the medication.

The decline of the indoor flea population follows a predictable pattern:

Day 0–1: Adult fleas on the treated pet die; immediate drop in new bites.
Day 2–5: Remaining adults on other hosts or in the environment die from contact with contaminated fur or blood.
Day 6–14: Hatchlings from eggs laid before treatment emerge; they die without a blood meal from a treated host.
Day 15–30: Residual eggs and pupae complete their cycle; without a viable adult host, the population collapses.

Effective control of the household burden requires concurrent environmental measures—vacuuming, washing bedding, and applying an insect growth regulator—to interrupt the life cycle and prevent re‑infestation. After a month of consistent spot‑on use and hygiene practices, flea counts typically fall below detectable levels.

What to Expect and When to Seek Veterinary Advice

Signs of Effective Treatment

Decreased Flea Activity

After a spot‑on product is applied to the animal’s neck, flea activity drops noticeably within the first few hours. The insecticide spreads across the skin, reaching the bloodstream and affecting fleas that bite the host. Within 6–12 hours most fleas become lethargic, lose the ability to jump, and cease feeding.

Complete mortality generally occurs within 24–48 hours. By the end of the second day, the majority of the population on the animal is dead, and any surviving fleas are immobilized and unable to reproduce. Observers can expect a rapid reduction in visible scratching, fewer flea sightings, and a marked decline in the insects’ movement on the pet’s coat.

Finding Dead Fleas

After a spot‑on flea treatment is applied to the neck, most adult fleas begin to die within 12 hours; complete elimination of the initial infestation typically occurs by 24–48 hours. The insecticide spreads across the skin surface, reaching parasites on the host and in the immediate environment, so dead fleas appear on the animal and on surrounding surfaces during this period.

To locate deceased fleas, follow these steps:

Examine the pet’s coat, especially the neck, shoulders, and base of the tail. Use a fine-tooth comb, moving from the skin outward; dead insects will cling to the comb or fall onto a white towel.
Check bedding, grooming tools, and floor mats. Lightly shake or tap each item over a white sheet; dead fleas drop as dark specks.
Inspect the immediate environment (carpet edges, furniture seams). Use a handheld vacuum with a narrow nozzle, pausing briefly to view the collection bag or canister for fallen insects.

Confirming mortality requires visual verification. Dead fleas are immobile, flattened, and often appear gray‑brown. If live movement is observed, the treatment may be ineffective or the infestation includes resistant strains.

If no dead fleas are detected after 48 hours, consider the following actions:

Verify correct dosage and product expiration date.
Ensure the pet’s skin was not wet or heavily oiled at the time of application, which can impede absorption.
Repeat treatment according to label instructions or switch to an alternative class of insecticide.

When to Reapply or Reconsider Treatment

Persistent Fleas

Fleas that survive the initial application of a neck‑applied spot‑on product are often referred to as persistent. These insects may have been shielded by a thick coat, recent bathing, or a genetic resistance to the active ingredient. Because the medication spreads through the skin’s oil layer, any barrier that delays absorption allows a subset of fleas to remain alive for several days after treatment.

Typical mortality pattern after a correct dose:

12–24 hours: most susceptible fleas die; observable reduction in activity.
24–48 hours: the majority of the population is eliminated; occasional survivors may still be seen.
48–72 hours: residual fleas usually succumb; numbers approach zero in most cases.
Beyond 72 hours: any remaining insects are likely resistant or protected by environmental factors; additional intervention may be required.

Factors that extend flea survival include:

Inadequate dose relative to animal weight.
Heavy grooming or frequent bathing that removes the product.
Use of shampoos or conditioners containing oil‑soluble agents that interfere with distribution.
Presence of a resistant flea strain in the environment.

When persistent fleas are detected after the expected three‑day window, recommended actions are to verify correct dosing, re‑apply the product according to label instructions, and eliminate environmental reservoirs through vacuuming, washing bedding, and treating the home with an appropriate insecticide. Continuous monitoring for at least two weeks ensures that the life cycle is fully interrupted.

Signs of Allergic Reactions

Spot‑on flea treatments applied to the neck can provoke allergic reactions in susceptible pets. Recognizing these reactions is essential for timely intervention.

Redness or inflammation at the application site
Swelling, especially around the head, ears, or neck
Intense scratching, biting, or licking of the treated area
Development of hives or raised, itchy bumps on the skin

Systemic manifestations may accompany or follow cutaneous signs:

Labored breathing or wheezing
Rapid heart rate or weak pulse
Vomiting, diarrhea, or loss of appetite
Lethargy, collapse, or seizures in severe cases

Reactions typically emerge within minutes to a few hours after the product contacts the skin, though delayed responses can occur up to 24 hours later. Prompt veterinary evaluation is required if any of these signs appear. Immediate measures include washing the area with mild soap and water, removing excess product, and preventing the animal from licking the site until professional guidance is received.

Common Misconceptions About Flea Treatment

Expecting Instantaneous Disappearance of All Fleas

Spot‑on products applied to the nape of a pet do not eradicate every flea the instant the bottle is opened. The active ingredients spread across the skin, enter the bloodstream, and kill parasites only after they bite the host. Consequently, a visible reduction in adult fleas typically requires several hours, while complete elimination may take up to 24 hours.

The process unfolds in stages:

Contact kill – fleas that are already feeding die within 4–8 hours after exposure to the medication.
Residual effect – newly acquired fleas are killed when they attempt to feed during the next 24–48 hours.
Egg and larva control – eggs laid before treatment hatch, but larvae fail to develop because the environment lacks a living host; this cycle finishes in 5–7 days.

Factors influencing the speed of decline include:

Concentration and spectrum of the active compound.
Size and hair density of the animal, which affect dispersion.
Severity of the existing infestation.
Ambient temperature; warmer conditions accelerate flea metabolism and drug absorption.

Expecting an immediate, total disappearance of all fleas is unrealistic. Effective control requires patience, a follow‑up dose according to the product label, and concurrent treatment of the living environment to interrupt the life cycle. Monitoring the pet for new bites and cleaning bedding, carpets, and upholstery will ensure the population is fully suppressed.

The Importance of Treating the Environment

Spot‑on products applied to the neck begin killing adult fleas on the host within minutes; most manufacturers report 90 % mortality by the end of the first hour and complete elimination of feeding adults within 24 hours. Eggs, larvae and pupae that have already left the animal remain viable in the surroundings for up to three weeks, emerging as new adults if the environment is not addressed.

The environment serves as a reservoir for immature stages. Without concurrent treatment of bedding, carpets and floor seams, surviving stages repopulate the pet after the spot‑on medication has cleared from the animal’s skin. This cycle prolongs infestation, increases the likelihood of secondary skin infections, and raises the risk of allergic reactions in both pets and owners.

Effective environmental control includes the following actions:

Vacuum all carpeted areas, upholstered furniture and pet bedding; discard the vacuum bag or clean the canister immediately.
Wash all washable fabrics (blankets, cushion covers) in hot water (≥ 60 °C) and dry on high heat.
Apply a residual insecticide labeled for indoor flea control, covering cracks, baseboards and under furniture.
Use an insect growth regulator (IGR) spray or fogger to interrupt development of eggs and larvae.
Repeat vacuuming and IGR application weekly for at least three weeks to cover the full flea life cycle.

Neglecting these steps allows the flea population to rebound, rendering the spot‑on treatment ineffective over time and exposing the household to ongoing irritation and potential disease transmission. Comprehensive environmental management thus ensures lasting eradication and protects animal health.